When using the Replace With option and then undoing it, upon engine restart the Widget Blueprint's UI components are all removed from the Widget Blueprint. It seems the undo is crucial to the issue, since without it I wasn't able to reproduce the issue.

I tested this in both //UE4/Release-4.26 @ CL 14830424 and //UE5/Main @ CL 15183992 and I was able to reproduce in both. I also tested in //UE4/Release-4.25 @ CL 14818863 and this did not occur, so marking this as a Regression.

Steps to Reproduce
  1. Create a Widget
  2. Remove the Canvas Panel at the root
  3. Add a VerticalBox in it
  4. In that VerticalBox add a Button
  5. Right click on the vertical box, choose Replace With->Horizontalbox
  6. Undo the replace
  7. Save the Widget Blueprint
  8. Exit the Editor
  9. Restart the Editor
  10. Open the Widget

The button will disapear and you will see "Removed unused Widget 'VButton' " in the Compiler Results.


When restarting the Editor, Widget Blueprints won't clear their UI components on an editor restart

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ComponentUE - Editor - UI Systems
Affects Versions4. access
Target Fix4.26.1
Fix Commit15222532
Main Commit15739932
Release Commit15222532
CreatedJan 25, 2021
ResolvedJan 27, 2021
UpdatedApr 27, 2021