Drag and drop operations don't work correctly when "Render on Phase" is enabled in a retainer box. When "Render on Phase" is disabled the drag and drop operations work as expected.
In 4.23.1 the drag and drop operations with "Render on Phase" enabled or disabled.
Attached is a 4.24 example project.
Found in 4.24.2 CL#10758860
Reproduced in 4.25 Main CL#11178322
1. Create an user widget blueprint (TestDraggable) that uses a retainer box with "Render on Phase".
2. Add a button underneath for visibility.
3. Override "OnMouseButtonDown", "OnPreviewMouseButtonDown", and "OnDragDetected" so drag and drop events work with this widget (see attached images).
4. Create another user widget blueprint (TestDrapParent) that has a TestDraggable in it.
5. In the level blueprint create a TestDrapParent widget and add it to the viewport.
6. Play the scene and drag the TestDraggable and attempt to place it somewhere else on screen.
Result: The drag and drop operation doesn't work as expected.
Expected: The drag and drop operation works as expected.
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-87885 in the post.