Crash on setting Material in Element 1 of Combined Mesh

Crash on clearing or setting the second or third material slot in the Static Mesh Editor on an imported combined FBX Mesh.

Also Reproduced in Main Promotable-CL-2484152 (Perforce)

NOTE: User is on the Promoted Build Branch from GitHub, tested with the GitHub version of the Editor and Main Perforce Builds

1. Open QAGame Editor
2. Import Attached SM_ThreeShapes.fbx with Combined Meshes checked true
3. Open newly imported Mesh in Static Mesh Editor
4. In Element 1, place a new material

RESULTS: CRASH to Desktop

EXPECTED: New Material chosen for Element 1

Assertion failed: Info.MaterialIndex == SlotIndex [Link Removed] [Line: 1257]

KERNELBASE.dll

{0x000007fefcea940d}

+ 0 bytes
UE4Editor-Core.dll!FOutputDeviceWindowsError::Serialize()

{0x000007feb915b5f4}

+ 0 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\c
UE4Editor-Core.dll!FOutputDevice::Logf__VA()

{0x000007feb8fa5778}

+ 159 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\c
UE4Editor-Core.dll!FDebug::AssertFailed()

{0x000007feb8f83832}

+ 65 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\c
UE4Editor-StaticMeshEditor.dll!FMeshSectionSettingsLayout::OnMaterialChanged()

{0x000007fea5a3d820}

+ 0 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\editor\st
UE4Editor-StaticMeshEditor.dll!TBaseSPMethodDelegateInstance<0,FMeshSectionSettingsLayout,0,TTypeWrapper<void> __cdecl(UMaterialInterface * __ptr64,UMaterialInterface * __ptr64,int,bool)>::Execute()

{0x000007fea5a13dae}

+ 53 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\c
UE4Editor-StaticMeshEditor.dll!TBaseSPMethodDelegateInstance<0,FMeshSectionSettingsLayout,0,void __cdecl(UMaterialInterface * __ptr64,UMaterialInterface * __ptr64,int,bool)>::ExecuteIfSafe()

{0x000007fea5a1561e}

+ 29 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\c
UE4Editor-PropertyEditor.dll!FMaterialItemView::ReplaceMaterial()

{0x000007feb2ff233b}

+ 0 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\editor\pr
UE4Editor-PropertyEditor.dll!TBaseSPMethodDelegateInstance<0,FMaterialItemView,0,TTypeWrapper<void> __cdecl(FAssetData const & __ptr64)>::Execute()

{0x000007feb2f6ca37}

+ 14 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\c
UE4Editor-PropertyEditor.dll!TBaseSPMethodDelegateInstance<0,FMaterialItemView,0,void __cdecl(FAssetData const & __ptr64)>::ExecuteIfSafe()

{0x000007feb2f6f09c}

+ 11 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\c
UE4Editor-PropertyEditor.dll!SPropertyEditorAsset::SetValue()

{0x000007feb3159ad6}

+ 0 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\editor\pr
UE4Editor-PropertyEditor.dll!TBaseSPMethodDelegateInstance<0,SPropertyEditorAsset,0,TTypeWrapper<void> __cdecl(FAssetData const & __ptr64)>::Execute()

{0x000007feb30e099c}

+ 35 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\c
UE4Editor-PropertyEditor.dll!TBaseSPMethodDelegateInstance<0,SPropertyEditorAsset,0,void __cdecl(FAssetData const & __ptr64)>::ExecuteIfSafe()

{0x000007feb30e3cdc}

+ 11 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\c
UE4Editor-PropertyEditor.dll!SPropertyMenuAssetPicker::OnAssetSelected()

{0x000007feb31183d6}

+ 0 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\editor\pr
UE4Editor-PropertyEditor.dll!TBaseSPMethodDelegateInstance<0,SPropertyMenuAssetPicker,0,TTypeWrapper<void> __cdecl(FAssetData const & __ptr64)>::Execute()

{0x000007feb30e158c}

+ 35 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\c
UE4Editor-PropertyEditor.dll!TBaseSPMethodDelegateInstance<0,SPropertyMenuAssetPicker,0,void __cdecl(FAssetData const & __ptr64)>::ExecuteIfSafe()

{0x000007feb30e443c}

+ 11 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\c
UE4Editor-ContentBrowser.dll!SAssetView::AssetSelectionChanged()

{0x000007feaa4c74de}

+ 141 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\editor\co
UE4Editor-ContentBrowser.dll!TBaseSPMethodDelegateInstance<0,SAssetView,0,TTypeWrapper<void> __cdecl(TSharedPtr<FAssetViewItem,0>,enum ESelectInfo::Type)>::Execute()

{0x000007feaa532a4a}

+ 55 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\c
UE4Editor-ContentBrowser.dll!TBaseSPMethodDelegateInstance<0,SAssetView,0,void __cdecl(TSharedPtr<FAssetViewItem,0>,enum ESelectInfo::Type)>::ExecuteIfSafe()

{0x000007feaa53ef35}

+ 40 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\c
UE4Editor-ContentBrowser.dll!TBaseDelegate<void,TSharedPtr<FAssetViewItem,0>,enum ESelectInfo::Type>::ExecuteIfBound()

{0x000007feaa53c131}

+ 41 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\c
UE4Editor-ContentBrowser.dll!SListView<TSharedPtr<FAssetViewItem,0> >::Private_SignalSelectionChanged()

{0x000007feaa5e8b35}

+ 33 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\s
UE4Editor-ContentBrowser.dll!STableRow<TSharedPtr<FAssetViewItem,0> >::OnMouseButtonUp()

{0x000007feaa5d3650}

+ 0 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\s
UE4Editor-Slate.dll!<lambda_de96dc3471181973108233c6db1f9843>::operator()()

{0x000007feb57c639c}

+ 24 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\s
UE4Editor-Slate.dll!FEventRouter::Route<FReply,FEventRouter::FToLeafmostPolicy,FPointerEvent,<lambda_de96dc3471181973108233c6db1f9843> >()

{0x000007feb577c967}

+ 21 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\s
UE4Editor-Slate.dll!FSlateApplication::ProcessMouseButtonUpEvent()

{0x000007feb5839c5e}

+ 78 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\s
UE4Editor-Slate.dll!FSlateApplication::OnMouseUp()

{0x000007feb5826fc9}

+ 16 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\s
UE4Editor-Core.dll!FWindowsApplication::ProcessDeferredMessage()

{0x000007feb90a0f02}

+ 12 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\c
UE4Editor-Core.dll!FWindowsApplication::DeferMessage()

{0x000007feb908ed1c}

+ 74 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\c
UE4Editor-Core.dll!FWindowsApplication::ProcessMessage()

{0x000007feb90a23f6}

+ 44 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\c
UE4Editor-Core.dll!FWindowsApplication::AppWndProc()

{0x000007feb908b4c3}

+ 0 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\c
USER32.dll

{0x0000000076d89bd1}

+ 0 bytes
USER32.dll

{0x0000000076d898da}

+ 0 bytes
UE4Editor-Core.dll!FWindowsPlatformMisc::PumpMessages()

{0x000007feb9154ff6}

+ 48 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\c
UE4Editor.exe!FEngineLoop::Tick()

{0x000000013fa76c3f}

+ 8 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\l
UE4Editor.exe!GuardedMain()

{0x000000013fa6758c}

+ 0 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\l
UE4Editor.exe!GuardedMainWrapper()

{0x000000013fa6760a}

+ 5 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\l
UE4Editor.exe!WinMain()

{0x000000013fa7a278}

+ 17 bytes [d:\buildfarm\buildmachine_++depot+ue4\engine\source\runtime\l
UE4Editor.exe!__tmainCRTStartup()

{0x000000013fa7b2a9}

+ 21 bytes [f:\dd\vctools\crt\crtw32\dllstuff\crtexe.c:618]
kernel32.dll

{0x0000000076c659ed}

+ 0 bytes
ntdll.dll

{0x0000000076e9c541} + 0 bytes
ntdll.dll {0x0000000076e9c541}

+ 0 bytes