Undo.SetTransformParent simply not undoing

This is in Unity 4.6.7. Using as indicated in the docs:
http://docs.unity3d.com/ScriptReference/Undo.html
http://docs.unity3d.com/ScriptReference/Undo.SetTransformParent.html

It's just not undoing the parenting. Has anyone else seen this? Is there some trick it it's usage that eludes me?

It's a simple reparenting action executed after a GUILayout.Button in an EditorWindow inherited class:

Code (csharp):

1. Undo.SetTransformParent(targetGO.transform, newParentGO.transform, "Move To Blah");

The parenting itself happens properly. But I can't get it to undo at all. I've tried Undo.RecordObject with all other parents involved as well. Nothing is working.

Anyone else seen anything like this?

 

how are you trying to do the undo? ctrl+z etc?

 

Keyboard shortcuts and using the Edit > Undo menu both have the same effect.

 

Really? No one? Logging as bug I guess.