Object in Hierarchy gets stuck if parented under a UIDocument object

Steps to reproduce:

1. Open the attached project
2. Open the SampleScene
3. Drag GameObject under the UIDocument to parent the Object
4. Try dragging the GameObject out to unparent it

Actual results: Dragging out the GameObject does not work, and it stays parented to the UI Document object

Expected results: GameObject can be unparented by dragging it outside the UI Document object in the Hierarchy

Reproducible with versions: 6000.3.0a5, 6000.3.7f1, 6000.4.0b7, 6000.5.0a6

Can’t test with versions: 6000.0.66f2, 6000.3.0a4 (Hierarchy V2 with UI Toolkit integration not available)

Tested on (OS): macOS 26.2, Windows 11