Imported heightmaps with 2x2 sections crash editor

Importing a heightmap with 2x2 segments seems to cause the editor to crash in 3 different instances:

1. Importing the same 2x2 segment landscape a second time after deleting the first instance
2. Attempting to delete the imported heightmap
3. Attempting to select windows/toolbars after import.

These instances have been difficult to narrow down, and have occurred on two PCs out of three tested internally.

Notes

• May be related to landscape rendering upon import.
• Two .r16 files included. Both reproduce crash, one is internally created, the other is a user created asset.

CrashReporter: [Link Removed]

Frequency 4/10

Regression (yes) issue (does not) occur in 4.11.2

1. Download attached .r16 file
2. Open Editor (any project)
3. Open Landscape Mode
4. Select Import from File
5. Select .r16 file from download location
6. Select "2x2" in "Sections Per Component"
7. Press Create

If the editor does not crash:

8. Select Place mode
9. Select Landscape
10. Delete Landscape

If editor does not crash:

11. Re-import landscape
12. Re-delete landscape

If editor does not crash:

13. repeat last two steps, move camera around

Results:

Editor sometimes will crash either with or without crash report window. Error window appears showing "Unreal Engine has stopped working".

Expected

Landscape is created, deleted, reimported multiple times, editor does not crash.

MachineId:409D523543AE785961A2788C698A2F90
EpicAccountId:89e014249c0a480eb18ea5b683d2eb3c

Assertion failed: Result == FPropertyAccess::Success [Link Removed] [Line: 989]

UE4Editor_CoreUObject!UObjectBaseUtility::GetFullName() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\coreuobject\private\uobject\uobjectbaseutility.cpp:78]
UE4Editor_CoreUObject!FRealtimeGC::MarkObjectsAsUnreachable<0>() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\coreuobject\private\uobject\garbagecollection.cpp:718]
UE4Editor_CoreUObject!FRealtimeGC::PerformReachabilityAnalysis() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\coreuobject\private\uobject\garbagecollection.cpp:806]
UE4Editor_CoreUObject!CollectGarbageInternal() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\coreuobject\private\uobject\garbagecollection.cpp:1246]
UE4Editor_CoreUObject!CollectGarbage() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\coreuobject\private\uobject\garbagecollection.cpp:1341]
UE4Editor_UnrealEd!UUnrealEdEngine::edactDeleteSelected() [d:\build\++ue4+release-4.12+compile\sync\engine\source\editor\unrealed\private\editoractor.cpp:878]
UE4Editor_UnrealEd!UUnrealEdEngine::Exec_Actor() [d:\build\++ue4+release-4.12+compile\sync\engine\source\editor\unrealed\private\unrealedsrv.cpp:2590]
UE4Editor_UnrealEd!UUnrealEdEngine::Exec() [d:\build\++ue4+release-4.12+compile\sync\engine\source\editor\unrealed\private\unrealedsrv.cpp:801]
UE4Editor_UnrealEd!UEditorEngine::Exec() [d:\build\++ue4+release-4.12+compile\sync\engine\source\editor\unrealed\private\editorserver.cpp:5494]
UE4Editor_UnrealEd!UUnrealEdEngine::Exec() [d:\build\++ue4+release-4.12+compile\sync\engine\source\editor\unrealed\private\unrealedsrv.cpp:744]
UE4Editor_LevelEditor!FLevelEditorActionCallbacks::ExecuteExecCommand() [d:\build\++ue4+release-4.12+compile\sync\engine\source\editor\leveleditor\private\leveleditoractions.cpp:1591]
UE4Editor_LevelEditor!TBaseStaticDelegateInstance<void __cdecl(void),FString>::ExecuteIfSafe() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:1021]
UE4Editor_Slate!FUICommandList::ConditionalProcessCommandBindings() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\commands\uicommandlist.cpp:206]
UE4Editor_Slate!FUICommandList::ProcessCommandBindings() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\commands\uicommandlist.cpp:150]
UE4Editor_UnrealEd!SEditorViewport::OnKeyDown() [d:\build\++ue4+release-4.12+compile\sync\engine\source\editor\unrealed\private\seditorviewport.cpp:99]
UE4Editor_LevelEditor!SLevelViewport::OnKeyDown() [d:\build\++ue4+release-4.12+compile\sync\engine\source\editor\leveleditor\private\slevelviewport.cpp:420]
UE4Editor_Slate!<lambda_7c66138389984533974223608bc6375f>::operator()() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4232]
UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FBubblePolicy,FKeyEvent,<lambda_7c66138389984533974223608bc6375f> >() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:215]
UE4Editor_Slate!FEventRouter::RouteAlongFocusPath<FEventRouter::FBubblePolicy,<lambda_7c66138389984533974223608bc6375f>,FKeyEvent>() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:197]
UE4Editor_Slate!FSlateApplication::ProcessKeyDownEvent() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4230]
UE4Editor_Slate!FSlateApplication::OnKeyDown() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4147]
UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:1345]
UE4Editor_Core!FWindowsApplication::DeferMessage() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:1850]
UE4Editor_Core!FWindowsApplication::ProcessMessage() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:745]
UE4Editor_Core!FWindowsApplication::AppWndProc() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:667]
user32
user32
UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\core\private\windows\windowsplatformmisc.cpp:903]
UE4Editor!FEngineLoop::Tick() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\launch\private\launchengineloop.cpp:2729]
UE4Editor!GuardedMain() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\launch\private\launch.cpp:148]
UE4Editor!GuardedMainWrapper() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() [d:\build\++ue4+release-4.12+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:200]
UE4Editor!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:264]
kernel32
ntdll