Widget defaults not updated when modified on a base widget class via the hierarchy

A licensee has reported an inconsistency in how modified base widget class defaults are propagated to children. When modified via the UMG Designer Graph's Class Defaults, derived classes will be marked as modified and reflect the new defaults as expected. However, when modified via the Designer view's hierarchy, derived widgets will retain the old default and serialize it once resaved.

1. Create a BP UserWidget "WBP_A"
2. Add a "button" widget in the Designer just to have something visual
3. Create a BP UserWidget "WBP_B" derived from "WBP_A"
4. Create a BP UserWidget "WBP_Screen"
5. Add "WBP_B" as a child to its root in the "Designer"
6. Keep all 3 assets open in the Editor
7. Go to WBP_A, select "Graph" -> "Class Defaults" -> "Appearance" -> "Color and Opacity" - > Change to a random color of your choice
8. Observe: WBP_B and WBP_Screen have a * next to their name in the tab and if you open them you can see that they adopted the color in the "Designer" view
9. Save all assets
10. Go to WBP_A again and select "Designer" -> "Hierarchy" -> "[Button]" -> Details Panel ->"Color and Opacity" - > Change to a random color of your choice
11. Observe: WBP_B and WBP_Screen have no * next to their name in the tab and if you open them you can see that they have not adopted the color in the "Designer" view
12. Observe: If you look at the "Color and Opacity" in the Class Defaults of WBP_B and WBP_Screen, now there is a "revert to defaults" button available.

Expected behavior: 10 should behave like 8

Overriding Serialize() does not work for WIDGETS