Crash when Building Lighting on Macs with Lighting Scenarios

A crash occurs when you building lighting with a project using Lighting Scenarios on a Mac.

I attempted to reproduce the issue using a new blank project, but was unable to get the crash to occur. The user reporting the issue has provided a project for testing which crashes immediately upon building lighting.

I also tested this issue on PC and the crash does not occur.

1. Download and Open attached project.
2. Build Lighting.

Outcome Crash occurs.

Expected The lighting builds without a crash.

libsystem_kernel.dylib!<Unknown>
libsystem_kernel.dylib!<Unknown>
libobjc.A.dylib!Unknown()
libobjc.A.dylib!Unknown()
libobjc.A.dylib!Unknown()
CoreFoundation!Unknown()
Foundation!Unknown()
UE4Editor-Core.dylib!FMacApplication::OnWindowDidResize(TSharedRef<FMacWindow,()
UE4Editor-Core.dylib!<Unknown>
UE4Editor-Core.dylib!<Unknown>
UE4Editor-Core.dylib!FCocoaRunLoopSource::Process()
UE4Editor-Core.dylib!<Unknown>
CoreFoundation!Unknown()
CoreFoundation!Unknown()
CoreFoundation!Unknown()
CoreFoundation!Unknown()
UE4Editor-Core.dylib!PerformBlockOnThread(FCocoaRunLoopSource&, void()
UE4Editor-Core.dylib!MainThreadCall(void()
UE4Editor-Core.dylib!FMacWindow::ReshapeWindow()
UE4Editor-SlateCore.dylib!SWindow::Resize()
UE4Editor-Slate.dylib!PrepassWindowAndChildren(TSharedRef<SWindow,()
UE4Editor-Slate.dylib!FSlateApplication::DrawPrepass(TSharedPtr<SWindow,()
UE4Editor-Slate.dylib!FSlateApplication::PrivateDrawWindows(TSharedPtr<SWindow,()
UE4Editor-Slate.dylib!FSlateApplication::DrawWindows()
UE4Editor-Slate.dylib!FSlateApplication::TickApplication()
UE4Editor-Slate.dylib!FSlateApplication::AddModalWindow(TSharedRef<SWindow, (ESPMode)0>, TSharedPtr<SWidget const,()
UE4Editor-UnrealEd.dylib!UEditorEngine::EditorAddModalWindow(TSharedRef<SWindow,()
UE4Editor-UnrealEd.dylib!FSuppressableWarningDialog::ShowModal()
UE4Editor-UnrealEd.dylib!FStaticLightingSystem::BeginLightmassProcess()
UE4Editor-UnrealEd.dylib!FStaticLightingManager::CreateStaticLightingSystem()
UE4Editor-UnrealEd.dylib!UEditorEngine::BuildLighting()
UE4Editor-UnrealEd.dylib!FEditorBuildUtils::EditorBuild()
UE4Editor-LevelEditor.dylib!TBaseStaticDelegateInstance<void ()>::ExecuteIfSafe()
UE4Editor-Slate.dylib!FUICommandList::ExecuteAction(TSharedRef<FUICommandInfo const,()
UE4Editor-Slate.dylib!SMenuEntryBlock::OnClicked()
UE4Editor-Slate.dylib!SMenuEntryBlock::OnMenuItemButtonClicked()
UE4Editor-Slate.dylib!TBaseSPMethodDelegateInstance<false, SMenuEntryBlock, (ESPMode)0, FReply ()>::Execute()
UE4Editor-Slate.dylib!SButton::OnMouseButtonUp()
UE4Editor-Slate.dylib!SMenuEntryButton::OnMouseButtonUp()
UE4Editor-Slate.dylib!FSlateApplication::RoutePointerUpEvent()
UE4Editor-Slate.dylib!FSlateApplication::ProcessMouseButtonUpEvent()
UE4Editor-Slate.dylib!FSlateApplication::OnMouseUp()
UE4Editor-Core.dylib!FMacApplication::ProcessEvent()
UE4Editor-Core.dylib!FMacApplication::ProcessDeferredEvents()
UE4Editor-Slate.dylib!FSlateApplication::TickPlatform()
UE4Editor-Slate.dylib!FSlateApplication::Tick()
UE4Editor!FEngineLoop::Tick()
UE4Editor!GuardedMain()
UE4Editor!<Unknown>
UE4Editor-Core.dylib!<Unknown>
Foundation!Unknown()
libsystem_pthread.dylib!<Unknown>
libsystem_pthread.dylib!<Unknown>
libsystem_pthread.dylib!<Unknown>