[CrashReport] UE4Editor_MaterialEditor!SMaterialLayersFunctionsInstanceTree::UpdateThumbnailMaterial() [smateriallayersfunctionstree.cpp:1128]

 1114       		for (TSharedPtr<FStackSortedData> Group : AssetChild->Children)
 1115       		{
 1116       			if (Group->ParameterInfo.Association == InAssociation)
 1117       			{
 1118       				ParameterGroups.Add(Group->Group);
 1119       			}
 1120       		}
 1121       		if (InAssociation == EMaterialParameterAssociation::LayerParameter)
 1122       		{
 1123       			MaterialToUpdate = StoredLayerPreviews[InIndex];
 1124       		}
 1125       		if (InAssociation == EMaterialParameterAssociation::BlendParameter)
 1126       		{
 1127 ***** 			MaterialToUpdate = StoredBlendPreviews[InIndex - 1];
 1128       		}
 1129       
 1130       	}

Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\Build\++UE4+Release-4.19+Compile\Sync\Engine\Source\Runtime\Core\Public\Containers/Array.h] [Line: 610] Array index out of bounds: -1 from an array of size 1

UE4Editor_MaterialEditor!SMaterialLayersFunctionsInstanceTree::UpdateThumbnailMaterial() [smateriallayersfunctionstree.cpp:1128]
UE4Editor_MaterialEditor!TBaseSPMethodDelegateInstance<0,SMaterialLayersFunctionsInstanceTree,0,TTypeWrapper<void> __cdecl() [delegateinstancesimpl.h:269]
UE4Editor_MaterialEditor!TBaseSPMethodDelegateInstance<0,SMaterialLayersFunctionsInstanceTree,0,void __cdecl() [delegateinstancesimpl.h:345]
UE4Editor_PropertyEditor!TBaseMulticastDelegate<void>::Broadcast() [delegatesignatureimpl.inl:937]
UE4Editor_PropertyEditor!FPropertyNode::BroadcastPropertyChangedDelegates() [propertynode.cpp:2488]
UE4Editor_PropertyEditor!FPropertyNode::NotifyPostChange() [propertynode.cpp:2437]
UE4Editor_PropertyEditor!FPropertyHandleBase::NotifyPostChange() [propertyhandleimpl.cpp:3038]
UE4Editor_MaterialEditor!FMaterialPropertyHelpers::SetVectorChannelMaskValue() [materialpropertyhelpers.cpp:1067]
UE4Editor_MaterialEditor!TBaseStaticDelegateInstance<TTypeWrapper<void> __cdecl() [delegateinstancesimpl.h:736]
UE4Editor_PropertyEditor!SPropertyEditorCombo::SendToObjects() [spropertyeditorcombo.cpp:218]
UE4Editor_PropertyEditor!SPropertyEditorCombo::OnComboSelectionChanged() [spropertyeditorcombo.cpp:192]
UE4Editor_PropertyEditor!TBaseSPMethodDelegateInstance<0,SPropertyEditorCombo,0,TTypeWrapper<void> __cdecl() [delegateinstancesimpl.h:269]
UE4Editor_PropertyEditor!TBaseSPMethodDelegateInstance<0,SPropertyEditorCombo,0,void __cdecl() [delegateinstancesimpl.h:345]
UE4Editor_PropertyEditor!TBaseDelegate<void,TSharedPtr<FString,0>,enum ESelectInfo::Type>::ExecuteIfBound() [delegatesignatureimpl.inl:624]
UE4Editor_PropertyEditor!SPropertyComboBox::OnSelectionChangedInternal() [spropertycombobox.cpp:114]
UE4Editor_PropertyEditor!TBaseSPMethodDelegateInstance<0,SPropertyComboBox,0,TTypeWrapper<void> __cdecl() [delegateinstancesimpl.h:269]
UE4Editor_PropertyEditor!TBaseSPMethodDelegateInstance<0,SPropertyComboBox,0,void __cdecl() [delegateinstancesimpl.h:345]
UE4Editor_PropertyEditor!TBaseDelegate<void,TSharedPtr<FString,0>,enum ESelectInfo::Type>::ExecuteIfBound() [delegatesignatureimpl.inl:624]
UE4Editor_PropertyEditor!SComboBox<TSharedPtr<FString,0> >::OnSelectionChanged_Internal() [scombobox.h:455]
UE4Editor_PropertyEditor!TBaseSPMethodDelegateInstance<0,SComboBox<TSharedPtr<FString,0> >,0,TTypeWrapper<void> __cdecl() [delegateinstancesimpl.h:269]
UE4Editor_PropertyEditor!TBaseSPMethodDelegateInstance<0,SComboBox<TSharedPtr<FString,0> >,0,void __cdecl() [delegateinstancesimpl.h:345]
UE4Editor_PropertyEditor!TBaseDelegate<void,TSharedPtr<FString,0>,enum ESelectInfo::Type>::ExecuteIfBound() [delegatesignatureimpl.inl:624]
UE4Editor_PropertyEditor!SListView<TSharedPtr<FString,0> >::Private_SignalSelectionChanged() [slistview.h:729]
UE4Editor_PropertyEditor!STableRow<TSharedPtr<FString,0> >::OnMouseButtonUp() [stablerow.h:474]
UE4Editor_Slate!<lambda_1002768c627006711ef2f351a87ec0e7>::operator() [slateapplication.cpp:5428]
UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FToLeafmostPolicy,FPointerEvent,<lambda_1002768c627006711ef2f351a87ec0e7> >() [slateapplication.cpp:266]
UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent() [slateapplication.cpp:5417]
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent() [slateapplication.cpp:5915]
UE4Editor_Slate!FSlateApplication::OnMouseUp() [slateapplication.cpp:5895]
UE4Editor_ApplicationCore!FWindowsApplication::ProcessDeferredMessage() [windowsapplication.cpp:1726]
UE4Editor_ApplicationCore!FWindowsApplication::DeferMessage() [windowsapplication.cpp:2172]
UE4Editor_ApplicationCore!FWindowsApplication::ProcessMessage() [windowsapplication.cpp:889]
UE4Editor_ApplicationCore!FWindowsApplication::AppWndProc() [windowsapplication.cpp:726]
user32!UserCallWinProcCheckWow()
user32!DispatchMessageWorker()
UE4Editor_ApplicationCore!FWindowsPlatformApplicationMisc::PumpMessages() [windowsplatformapplicationmisc.cpp:129]
UE4Editor!FEngineLoop::Tick() [launchengineloop.cpp:3263]
UE4Editor!GuardedMain() [launch.cpp:166]
UE4Editor!GuardedMainWrapper() [launchwindows.cpp:134]
UE4Editor!WinMain() [launchwindows.cpp:210]
UE4Editor!__scrt_common_main_seh() [exe_common.inl:253]
kernel32!BaseThreadInitThunk()
ntdll!RtlUserThreadStart()