Crash when Changing LOD Group on SpeedTree Assets

UE4Editor_Core!FDebug::AssertFailed() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\core\private\misc\assertionmacros.cpp:332]
UE4Editor_QuadricMeshReduction!TQuadricAttr<29>::Evaluate() [d:\build\++ue4+release-4.14+compile\sync\engine\source\developer\meshsimplifier\private\quadric.h:616]
UE4Editor_QuadricMeshReduction!TMeshSimplifier<TVertSimp<8>,29>::ComputeNewVerts() [d:\build\++ue4+release-4.14+compile\sync\engine\source\developer\meshsimplifier\private\meshsimplify.h:892]
UE4Editor_QuadricMeshReduction!TMeshSimplifier<TVertSimp<8>,29>::ComputeEdgeCollapseCost() [d:\build\++ue4+release-4.14+compile\sync\engine\source\developer\meshsimplifier\private\meshsimplify.h:910]
UE4Editor_QuadricMeshReduction!TMeshSimplifier<TVertSimp<8>,29>::InitCosts() [d:\build\++ue4+release-4.14+compile\sync\engine\source\developer\meshsimplifier\private\meshsimplify.h:398]
UE4Editor_QuadricMeshReduction!FQuadricSimplifierMeshReduction::Reduce() [d:\build\++ue4+release-4.14+compile\sync\engine\source\developer\meshsimplifier\private\quadricmeshreduction.cpp:339]
UE4Editor_MeshUtilities!FStaticMeshUtilityBuilder::ReduceLODs() [d:\build\++ue4+release-4.14+compile\sync\engine\source\developer\meshutilities\private\meshutilities.cpp:3737]
UE4Editor_MeshUtilities!FMeshUtilities::BuildStaticMesh() [d:\build\++ue4+release-4.14+compile\sync\engine\source\developer\meshutilities\private\meshutilities.cpp:4031]
UE4Editor_Engine!FStaticMeshRenderData::Cache() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\engine\private\staticmesh.cpp:1367]
UE4Editor_Engine!UStaticMesh::CacheDerivedData() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\engine\private\staticmesh.cpp:2221]
UE4Editor_Engine!UStaticMesh::Build() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\engine\private\staticmeshbuild.cpp:97]
UE4Editor_Engine!UStaticMesh::PostEditChangeProperty() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\engine\private\staticmesh.cpp:1864]
UE4Editor_CoreUObject!UObject::PostEditChange() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\coreuobject\private\uobject\obj.cpp:285]
UE4Editor_StaticMeshEditor!FLevelOfDetailSettingsLayout::OnLODGroupChanged() [d:\build\++ue4+release-4.14+compile\sync\engine\source\editor\staticmesheditor\private\staticmesheditortools.cpp:2553]
UE4Editor_StaticMeshEditor!TBaseSPMethodDelegateInstance<0,FLevelOfDetailSettingsLayout,0,TTypeWrapper<void> __cdecl(TSharedPtr<FString,0>,enum ESelectInfo::Type)>::Execute() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:318]
UE4Editor_StaticMeshEditor!TBaseSPMethodDelegateInstance<0,FLevelOfDetailSettingsLayout,0,void __cdecl(TSharedPtr<FString,0>,enum ESelectInfo::Type)>::ExecuteIfSafe() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:425]
UE4Editor_Slate!TBaseDelegate<void,TSharedPtr<FString,0>,enum ESelectInfo::Type>::ExecuteIfBound() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\core\public\delegates\delegatesignatureimpl.inl:609]
UE4Editor_Slate!STextComboBox::OnSelectionChanged() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\slate\private\widgets\input\stextcombobox.cpp:71]
UE4Editor_Slate!TBaseSPMethodDelegateInstance<0,STextComboBox,0,TTypeWrapper<void> __cdecl(TSharedPtr<FString,0>,enum ESelectInfo::Type)>::Execute() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:318]
UE4Editor_Slate!TBaseSPMethodDelegateInstance<0,STextComboBox,0,void __cdecl(TSharedPtr<FString,0>,enum ESelectInfo::Type)>::ExecuteIfSafe() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:425]
UE4Editor_Slate!TBaseDelegate<void,TSharedPtr<FString,0>,enum ESelectInfo::Type>::ExecuteIfBound() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\core\public\delegates\delegatesignatureimpl.inl:609]
UE4Editor_Slate!SComboBox<TSharedPtr<FString,0> >::OnSelectionChanged_Internal() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\slate\public\widgets\input\scombobox.h:420]
UE4Editor_Slate!TBaseSPMethodDelegateInstance<0,SComboBox<TSharedPtr<FString,0> >,0,TTypeWrapper<void> __cdecl(TSharedPtr<FString,0>,enum ESelectInfo::Type)>::Execute() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:318]
UE4Editor_Slate!TBaseSPMethodDelegateInstance<0,SComboBox<TSharedPtr<FString,0> >,0,void __cdecl(TSharedPtr<FString,0>,enum ESelectInfo::Type)>::ExecuteIfSafe() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:425]
UE4Editor_Slate!TBaseDelegate<void,TSharedPtr<FString,0>,enum ESelectInfo::Type>::ExecuteIfBound() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\core\public\delegates\delegatesignatureimpl.inl:609]
UE4Editor_Slate!SListView<TSharedPtr<FString,0> >::Private_SignalSelectionChanged() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\slate\public\widgets\views\slistview.h:638]
UE4Editor_Slate!STableRow<TSharedPtr<FString,0> >::OnMouseButtonUp() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\slate\public\widgets\views\stablerow.h:449]
UE4Editor_Slate!<lambda_8d0e9a1da76abd0a756a3a9d775f5ed1>::operator()() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5010]
UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FToLeafmostPolicy,FPointerEvent,<lambda_8d0e9a1da76abd0a756a3a9d775f5ed1> >() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:215]
UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:4999]
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5462]
UE4Editor_Slate!FSlateApplication::OnMouseUp() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5439]
UE4Editor_Core!FWindowsApplication::ProcessDeferredMessage() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:1652]
UE4Editor_Core!FWindowsApplication::DeferMessage() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:2071]
UE4Editor_Core!FWindowsApplication::ProcessMessage() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:814]
UE4Editor_Core!FWindowsApplication::AppWndProc() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\core\private\windows\windowsapplication.cpp:678]
user32
user32
UE4Editor_Core!FWindowsPlatformMisc::PumpMessages() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\core\private\windows\windowsplatformmisc.cpp:951]
UE4Editor!FEngineLoop::Tick() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\launch\private\launchengineloop.cpp:2811]
UE4Editor!GuardedMain() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\launch\private\launch.cpp:152]
UE4Editor!GuardedMainWrapper() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() [d:\build\++ue4+release-4.14+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:202]
UE4Editor!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:264]
kernel32
ntdll