Cannot undo the deleting of a virtual bone

In Persona, the user is not able to undo the deleting of a virtual bone.

1. Open QAGame in editor.
2. Open UE4_Mannequin_Skeleton in Persona.
3. Right-click any bone and select Add Virtual Bone > Any bone in the list.
4. Delete the virtual bone.
5. Undo.

RESULT:

You'll get a prompt saying the the delete was undone, but the virtual bone doesn't return.