Engine Crash When Double Clicking Anchor

When using the UMG Widget designer double clicking any part of a anchor the engine crashes.

Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\BuildFarm\buildmachine_++UE4+Release-4.11\Engine\Source\Runtime\Core\Public\Containers\Array.h] [Line: 785] 
Array index out of bounds: 0 from an array of size 0