This Jira was created from CrashReports submitted by the public due to the high number of occurrences. Descriptions from users are provided below.
Error message:
Assertion failed: Result == FPropertyAccess::Success [Link Removed] [Line: 989]
Source Context:
  917       			}
  918       		}
  919       
  920       		if( CurrentIndex != DragPreview.InsertIndex && DragPreview.InsertIndex != INDEX_NONE )
  921       		{
  922       			BuildMultiBoxWidget();
  923       		}
  924       	}
  925       
  926       }
  927       
  928       EVisibility SMultiBoxWidget::GetCustomizationVisibility( TWeakPtr<const FMultiBlock> BlockWeakPtr, TWeakPtr<SWidget> BlockWidgetWeakPtr ) const
  929       {
  930 ***** 	if( MultiBox->IsInEditMode() && BlockWidgetWeakPtr.IsValid() && BlockWeakPtr.IsValid() && (!DragPreview.PreviewBlock.IsValid() || BlockWeakPtr.Pin() != DragPreview.PreviewBlock->GetActualBlock() ) )
  931       	{
  932       		// If in edit mode and this is not the block being dragged, the customization widget should be visible if the default block beging customized would have been visible
  933       		return BlockWeakPtr.Pin()->GetAction().IsValid() && BlockWidgetWeakPtr.Pin()->GetVisibility() == EVisibility::Visible ? EVisibility::Visible : EVisibility::Collapsed;
  934       	}
  935       	else
  936       	{
  937       		return EVisibility::Collapsed;
  938       	}
  939       }
  940       
  941       FReply SMultiBoxWidget::OnDeleteBlockClicked( TWeakPtr<const FMultiBlock> BlockWeakPtr )
  942       {
  943       	if( BlockWeakPtr.IsValid() )
  944       	{
  945       		MultiBox->RemoveCustomMultiBlock( BlockWeakPtr.Pin().ToSharedRef() );}
Most recent user affected CL: 3005592
Logs: 
[Link Removed]
[Link Removed]
[Link Removed]
CrashReporter User Descriptions:
UE4Editor_Slate!SMultiBoxWidget::GetCustomizationVisibility() [multibox.cpp:931] UE4Editor_Slate!TMemberFunctionCaller<SMultiBoxWidget,EVisibility() [delegateinstanceinterface_variadics.h:161] UE4Editor_Slate!TBaseSPMethodDelegateInstance<1,SMultiBoxWidget,0,EVisibility __cdecl() [delegateinstancesimpl_variadics.inl:321] UE4Editor_SlateCore!TAttribute<EVisibility>::Get() [attribute.h:135] UE4Editor_SlateCore!SWidget::SlatePrepass() [swidget.cpp:372] UE4Editor_SlateCore!SWidget::SlatePrepass() [swidget.cpp:376] UE4Editor_SlateCore!SWidget::SlatePrepass() [swidget.cpp:376] UE4Editor_SlateCore!SWidget::SlatePrepass() [swidget.cpp:376] UE4Editor_SlateCore!SWidget::SlatePrepass() [swidget.cpp:376] UE4Editor_SlateCore!SWidget::SlatePrepass() [swidget.cpp:376] UE4Editor_SlateCore!SWidget::SlatePrepass() [swidget.cpp:376] UE4Editor_SlateCore!SWidget::SlatePrepass() [swidget.cpp:376] UE4Editor_SlateCore!SWidget::SlatePrepass() [swidget.cpp:376] UE4Editor_SlateCore!SWidget::SlatePrepass() [swidget.cpp:376] UE4Editor_SlateCore!SWidget::SlatePrepass() [swidget.cpp:376] UE4Editor_SlateCore!SWidget::SlatePrepass() [swidget.cpp:376] UE4Editor_SlateCore!SWidget::SlatePrepass() [swidget.cpp:376] UE4Editor_Slate!PrepassWindowAndChildren() [slateapplication.cpp:1107] UE4Editor_Slate!PrepassWindowAndChildren() [slateapplication.cpp:1116] UE4Editor_Slate!FSlateApplication::DrawPrepass() [slateapplication.cpp:1155] UE4Editor_Slate!FSlateApplication::PrivateDrawWindows() [slateapplication.cpp:1197] UE4Editor_Slate!FSlateApplication::DrawWindows() [slateapplication.cpp:969] UE4Editor_Slate!FSlateApplication::TickApplication() [slateapplication.cpp:1558] UE4Editor_Slate!FSlateApplication::Tick() [slateapplication.cpp:1350] UE4Editor!FEngineLoop::Tick() [launchengineloop.cpp:2810] UE4Editor!GuardedMain() [launch.cpp:148] UE4Editor!GuardedMainWrapper() [launchwindows.cpp:126] UE4Editor!WinMain() [launchwindows.cpp:200] UE4Editor!__scrt_common_main_seh() [exe_common.inl:264] kernel32!BaseThreadInitThunk() ntdll!RtlUserThreadStart()
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