Data Source and Attributes category fields become read only in UI Builder window after unsetting them if the UI element was also selected in Scene's Hierarchy

Steps to reproduce:

1. Open the attached project
2. Open the SampleScene
3. Open the test.UXML asset in UI Builder window
4. Select the Label UI Element in the Scene's Hierarchy
5. Select the Label UI Element in the UI Builder window
6. Right-click on the Data source field and select the "Unset Object Source" option
7. Observe the field

Actual results: Data source field becomes read-only

Expected results: The data source field is reset, but does not become read-only

Reproducible with versions: 6000.5.0a8, 6000.5.4f1, 6000.6.0b4, 6000.7.0a3

Not reproducible with versions: 6000.0.79f1, 6000.3.20f1, 6000.5.0a7

Tested on (OS): macOS 26.5.2