Ensure triggered in FBoundsCacheElement::GetValue when adding ISM instances in Construction Script

An ensure is triggered in FBoundsCacheElement::GetValue when adding instances to an InstancedStaticMeshComponent inside a Blueprint’s Construction Script. This occurs when the ISM component is navigation relevant and instances are added dynamically during construction, causing navigation registration to request cached bounds before CalcAndCacheNavigationBounds() has been called.

The issue reproduces in UE 5.6.1 and a recent build from Main stream (CL 46622846), but not in UE 5.5, confirming it as a regression.

For reference, CL 38213321 addressed a similar ensure triggered by AddInstancesInternal(), but the same fix was not applied to AddInstanceInternal(). Licensee suggests applying the same fix which consists of calling CalcAndCacheNavigationBounds() within the if (GetInstanceCount() == 1) branch of UInstancedStaticMeshComponent::AddInstanceInternal().

1. Open the attached repro project in UE 5.6.1 (or later).
2. Load the ReproMap level.
3. Observe that as soon as the level loads, an ensure is triggered in FBoundsCacheElement::GetValue (visible in the Output Log tab).

Callstack for UE 5.6.1 (launcher)
LogOutputDevice: Error: === Handled ensure: ===
LogOutputDevice: Error: Ensure condition failed: !bCheckValid || bIsValid [Link Removed] [Line: 128]
LogOutputDevice: Error: Stack:
LogOutputDevice: Error: [Callstack] 0x00007ffc9dfe3a69 UnrealEditor-Engine.dll!UInstancedStaticMeshComponent::GetNavigationBounds() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\InstancedStaticMesh.cpp:5401]
LogOutputDevice: Error: [Callstack] 0x00007ffc9d17408f UnrealEditor-Engine.dll!FNavigationElement::InitializeFromInterface() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\AI\Navigation\NavigationElement.cpp:87]
LogOutputDevice: Error: [Callstack] 0x00007ffc9d10636d UnrealEditor-Engine.dll!FNavigationElement::FNavigationElement() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\AI\Navigation\NavigationElement.cpp:64]
LogOutputDevice: Error: [Callstack] 0x00007ffc918b5b9b UnrealEditor-NavigationSystem.dll!UNavigationObjectRepository::RegisterNavRelevantObjectInternal() [D:\build\++UE5\Sync\Engine\Source\Runtime\NavigationSystem\Private\NavigationObjectRepository.cpp:135]
LogOutputDevice: Error: [Callstack] 0x00007ffc918b6ae7 UnrealEditor-NavigationSystem.dll!UNavigationSystemV1::RegisterNavRelevantObjectStatic() [D:\build\++UE5\Sync\Engine\Source\Runtime\NavigationSystem\Private\NavigationSystem.cpp:3613]
LogOutputDevice: Error: [Callstack] 0x00007ffc918b2938 UnrealEditor-NavigationSystem.dll!UNavigationSystemV1::RegisterComponentToNavOctree() [D:\build\++UE5\Sync\Engine\Source\Runtime\NavigationSystem\Private\NavigationSystem.cpp:3391]
LogOutputDevice: Error: [Callstack] 0x00007ffc9d1822eb UnrealEditor-Engine.dll!FNavigationSystem::RegisterComponent() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\AI\NavigationSystemBase.cpp:283]
LogOutputDevice: Error: [Callstack] 0x00007ffc9df83ad3 UnrealEditor-Engine.dll!UInstancedStaticMeshComponent::AddInstanceInternal() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\InstancedStaticMesh.cpp:3477]
LogOutputDevice: Error: [Callstack] 0x00007ffc9df8369a UnrealEditor-Engine.dll!UInstancedStaticMeshComponent::AddInstance() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\InstancedStaticMesh.cpp:3500]
LogOutputDevice: Error: [Callstack] 0x00007ffc9ce64936 UnrealEditor-Engine.dll!UInstancedStaticMeshComponent::execAddInstance() [D:\build\++UE5\Sync\Engine\Intermediate\Build\Win64\UnrealEditor\Inc\Engine\UHT\InstancedStaticMeshComponent.gen.cpp:333]
LogOutputDevice: Error: [Callstack] 0x00007ffd1c546164 UnrealEditor-CoreUObject.dll!UFunction::Invoke() [D:\build\++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\Class.cpp:7460]
LogOutputDevice: Error: [Callstack] 0x00007ffd1c9356af UnrealEditor-CoreUObject.dll!UObject::CallFunction() [D:\build\++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\ScriptCore.cpp:1175]
LogOutputDevice: Error: [Callstack] 0x00007ffd1c94ec14 UnrealEditor-CoreUObject.dll!UObject::ProcessContextOpcode() [D:\build\++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\ScriptCore.cpp:3153]
LogOutputDevice: Error: [Callstack] 0x00007ffd1c979b28 UnrealEditor-CoreUObject.dll!UObject::execLet() [D:\build\++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\ScriptCore.cpp:2895]
LogOutputDevice: Error: [Callstack] 0x00007ffd1c952fd8 UnrealEditor-CoreUObject.dll!ProcessLocalScriptFunction() [D:\build\++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\ScriptCore.cpp:1242]
LogOutputDevice: Error: [Callstack] 0x00007ffd1c95281c UnrealEditor-CoreUObject.dll!UObject::ProcessInternal() [D:\build\++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\ScriptCore.cpp:1371]
LogOutputDevice: Error: [Callstack] 0x00007ffd1c546164 UnrealEditor-CoreUObject.dll!UFunction::Invoke() [D:\build\++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\Class.cpp:7460]
LogOutputDevice: Error: [Callstack] 0x00007ffd1c950cb6 UnrealEditor-CoreUObject.dll!UObject::ProcessEvent() [D:\build\++UE5\Sync\Engine\Source\Runtime\CoreUObject\Private\UObject\ScriptCore.cpp:2211]
LogOutputDevice: Error: [Callstack] 0x00007ffc9d0a4b61 UnrealEditor-Engine.dll!AActor::ProcessEvent() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Actor.cpp:1456]
LogOutputDevice: Error: [Callstack] 0x00007ffc9d0a4c3d UnrealEditor-Engine.dll!AActor::ProcessUserConstructionScript() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\ActorConstruction.cpp:994]
LogOutputDevice: Error: [Callstack] 0x00007ffc9d078340 UnrealEditor-Engine.dll!AActor::ExecuteConstruction() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\ActorConstruction.cpp:921]
LogOutputDevice: Error: [Callstack] 0x00007ffc9d0b257e UnrealEditor-Engine.dll!AActor::RerunConstructionScripts() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\ActorConstruction.cpp:596]
LogOutputDevice: Error: [Callstack] 0x00007ffc9e1f9633 UnrealEditor-Engine.dll!ULevel::IncrementalRunConstructionScripts() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Level.cpp:2065]
LogOutputDevice: Error: [Callstack] 0x00007ffc9e1f9de5 UnrealEditor-Engine.dll!ULevel::IncrementalUpdateComponents() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Level.cpp:1878]
LogOutputDevice: Error: [Callstack] 0x00007ffc9e23aaf7 UnrealEditor-Engine.dll!ULevel::UpdateLevelComponents() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\Level.cpp:1663]
LogOutputDevice: Error: [Callstack] 0x00007ffc9f4ac93b UnrealEditor-Engine.dll!UWorld::UpdateWorldComponents() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\World.cpp:2804]
LogOutputDevice: Error: [Callstack] 0x00007ffc9aedb6c2 UnrealEditor-UnrealEd.dll!UEditorEngine::Map_Load() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\EditorServer.cpp:2689]
LogOutputDevice: Error: [Callstack] 0x00007ffc9aec5fdd UnrealEditor-UnrealEd.dll!UEditorEngine::HandleMapCommand() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\EditorServer.cpp:6219]
LogOutputDevice: Error: [Callstack] 0x00007ffc9aeab7bf UnrealEditor-UnrealEd.dll!UEditorEngine::Exec_Editor() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\EditorServer.cpp:5680]
LogOutputDevice: Error: [Callstack] 0x00007ffca1edc876 UnrealEditor-Core.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ffc9f851574 UnrealEditor-Engine.dll!UEngine::Exec() [D:\build\++UE5\Sync\Engine\Source\Runtime\Engine\Private\UnrealEngine.cpp:5143]
LogOutputDevice: Error: [Callstack] 0x00007ffc9bad8152 UnrealEditor-UnrealEd.dll!UUnrealEdEngine::Exec() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\UnrealEdSrv.cpp:662]
LogOutputDevice: Error: [Callstack] 0x00007ffc9b3212fd UnrealEditor-UnrealEd.dll!FEditorFileUtils::LoadMap() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\FileHelpers.cpp:3015]
LogOutputDevice: Error: [Callstack] 0x00007ffc5862159e UnrealEditor-EngineAssetDefinitions.dll!UAssetDefinition_World::OpenAssets() [D:\build\++UE5\Sync\Engine\Plugins\Editor\EngineAssetDefinitions\Source\Private\AssetDefinition_World.cpp:66]
LogOutputDevice: Error: [Callstack] 0x00007ffc90dd06c9 UnrealEditor-AssetTools.dll!FAssetDefinitionProxy::OpenAssetEditor() [D:\build\++UE5\Sync\Engine\Source\Developer\AssetTools\Private\AssetTools.cpp:259]
LogOutputDevice: Error: [Callstack] 0x00007ffc9b994616 UnrealEditor-UnrealEd.dll!UAssetEditorSubsystem::OpenEditorForAsset() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\Subsystems\AssetEditorSubsystem.cpp:583]
LogOutputDevice: Error: [Callstack] 0x00007ffc9b994d29 UnrealEditor-UnrealEd.dll!UAssetEditorSubsystem::OpenEditorForAssets_Advanced() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\Subsystems\AssetEditorSubsystem.cpp:652]
LogOutputDevice: Error: [Callstack] 0x00007ffc9b994a7f UnrealEditor-UnrealEd.dll!UAssetEditorSubsystem::OpenEditorForAssets() [D:\build\++UE5\Sync\Engine\Source\Editor\UnrealEd\Private\Subsystems\AssetEditorSubsystem.cpp:777]
LogOutputDevice: Error: [Callstack] 0x000001bbb3f2f76d UnrealEditor-ContentBrowserAssetDataSource.dll!ContentBrowserAssetData::EditOrPreviewAssetFileItems() [D:\build\++UE5\Sync\Engine\Plugins\Editor\ContentBrowser\ContentBrowserAssetDataSource\Source\ContentBrowserAssetDataSource\Private\ContentBrowserAssetDataCore.cpp:414]
LogOutputDevice: Error: [Callstack] 0x000001bbb3f2fa17 UnrealEditor-ContentBrowserAssetDataSource.dll!ContentBrowserAssetData::EditOrPreviewItems() [D:\build\++UE5\Sync\Engine\Plugins\Editor\ContentBrowser\ContentBrowserAssetDataSource\Source\ContentBrowserAssetDataSource\Private\ContentBrowserAssetDataCore.cpp:459]
LogOutputDevice: Error: [Callstack] 0x000001bbb3f0daab UnrealEditor-ContentBrowserAssetDataSource.dll!UContentBrowserAssetDataSource::BulkEditItems() [D:\build\++UE5\Sync\Engine\Plugins\Editor\ContentBrowser\ContentBrowserAssetDataSource\Source\ContentBrowserAssetDataSource\Private\ContentBrowserAssetDataSource.cpp:2663]
LogOutputDevice: Error: [Callstack] 0x00007ffc8bbc4d83 UnrealEditor-ContentBrowser.dll!SContentBrowser::OnItemsActivated() [D:\build\++UE5\Sync\Engine\Source\Editor\ContentBrowser\Private\SContentBrowser.cpp:3193]
LogOutputDevice: Error: [Callstack] 0x00007ffc8bb61492 UnrealEditor-ContentBrowser.dll!V::TBaseSPMethodDelegateInstance::Execute() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Delegates\DelegateInstancesImpl.h:292]
LogOutputDevice: Error: [Callstack] 0x00007ffc8bbc8562 UnrealEditor-ContentBrowser.dll!SAssetView::OnListMouseButtonDoubleClick() [D:\build\++UE5\Sync\Engine\Source\Editor\ContentBrowser\Private\SAssetView.cpp:5525]
LogOutputDevice: Error: [Callstack] 0x00007ffc8bb6bad7 UnrealEditor-ContentBrowser.dll!V::TBaseSPMethodDelegateInstance::ExecuteIfSafe() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Delegates\DelegateInstancesImpl.h:309]
LogOutputDevice: Error: [Callstack] 0x00007ffc8baabbe7 UnrealEditor-ContentBrowser.dll!TDelegate<void __cdecl(TSharedPtr<FAssetViewItem,1>),FDefaultDelegateUserPolicy>::ExecuteIfBound<void,0>() [D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Delegates\DelegateSignatureImpl.inl:635]
LogOutputDevice: Error: [Callstack] 0x00007ffc8bbe26ed UnrealEditor-ContentBrowser.dll!SListView<TSharedPtr<FAssetViewItem,1> >::Private_OnItemDoubleClicked() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Public\Widgets\Views\SListView.h:1154]
LogOutputDevice: Error: [Callstack] 0x00007ffc8bbc912e UnrealEditor-ContentBrowser.dll!STableRow<TSharedPtr<FAssetViewItem,1> >::OnMouseButtonDoubleClick() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Public\Widgets\Views\STableRow.h:438]
LogOutputDevice: Error: [Callstack] 0x00007ffd0da9512b UnrealEditor-Slate.dll!UE::Core::Private::ReallocTo<3,TSizedHeapAllocator<32,FMemory>::ForAnyElementType>() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:456]
LogOutputDevice: Error: [Callstack] 0x00007ffd0daf008a UnrealEditor-Slate.dll!FSlateApplication::RoutePointerDoubleClickEvent() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:5854]
LogOutputDevice: Error: [Callstack] 0x00007ffd0dadff4b UnrealEditor-Slate.dll!FSlateApplication::ProcessMouseButtonDoubleClickEvent() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:5839]
LogOutputDevice: Error: [Callstack] 0x00007ffd0dad35f7 UnrealEditor-Slate.dll!FSlateApplication::OnMouseDoubleClick() [D:\build\++UE5\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp:5802]
LogOutputDevice: Error: [Callstack] 0x00007ffd87b5f9a3 UnrealEditor-ApplicationCore.dll!FWindowsApplication::ProcessDeferredMessage() [D:\build\++UE5\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsApplication.cpp:3056]
LogOutputDevice: Error: [Callstack] 0x00007ffd87b47137 UnrealEditor-ApplicationCore.dll!FWindowsApplication::DeferMessage() [D:\build\++UE5\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsApplication.cpp:3570]
LogOutputDevice: Error: [Callstack] 0x00007ffd87b6299c UnrealEditor-ApplicationCore.dll!FWindowsApplication::ProcessMessage() [D:\build\++UE5\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsApplication.cpp:2725]
LogOutputDevice: Error: [Callstack] 0x00007ffd87b41171 UnrealEditor-ApplicationCore.dll!FWindowsApplication::AppWndProc() [D:\build\++UE5\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsApplication.cpp:1722]
LogOutputDevice: Error: [Callstack] 0x00007ffdc6307cf6 USER32.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ffdc630584d USER32.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ffd87b82316 UnrealEditor-ApplicationCore.dll!FWindowsPlatformApplicationMisc::PumpMessages() [D:\build\++UE5\Sync\Engine\Source\Runtime\ApplicationCore\Private\Windows\WindowsPlatformApplicationMisc.cpp:145]
LogOutputDevice: Error: [Callstack] 0x00007ff627ff871b UnrealEditor.exe!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff62801e5ac UnrealEditor.exe!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff62801e6ba UnrealEditor.exe!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff62802209e UnrealEditor.exe!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff628034e44 UnrealEditor.exe!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff6280380fa UnrealEditor.exe!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ffdc523e8d7 KERNEL32.DLL!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ffdc65e8d9c ntdll.dll!UnknownFunction []