Ctrl-Z does not function in Static Mesh Editor

When applying a Material to a Static Mesh in the SM Editor, an event for the undo function is never created and when you undo you are undoing the last action outside of the SM Editor.

Also reproduced in Main Promotable-CL-2564509 & Releases/4.8/Promoted-CL-2560772

1. Open QAGame Editor
2. Select any Static Mesh and place it in the level
3. Move the SM in the level from its placed location to a new location
4. Open the SM in the Static Mesh Editor
5. Assign a new Material to the Static Mesh
6. Undo, or CTRL-Z

RESULTS: The SM in the level moves back to its original location

EXPECTED: The SM Material assignment returns to its previous assignment.