Reproduction steps:
1. Create a new project
2. Enable Hierarchy Integration in Project Settings (Edit > Project Settings… > UI Toolkit)
3. GameObject > UI Toolkit > UI Document
4. Select newly created UIDocument GameObject and attach Source Asset to it in the Inspector by pressing “New” button
5. Open UI Builder by double-clicking on newly created Visual Tree Asset
6. Drag and drop any element in UI Builder Hierarchy and save changes
7. Select newly added Element in Editor Hierarchy and try to change any of the settings in Editor Inspector (e.g. Styles > Flex > Basis)

Actual result: Settings are editable but changes aren’t applied
Expected result: Settings are not editable

Reproducible with: 6000.5.0a1, 6000.5.0a6
Couldn’t reproduce with: 6000.0.66f2 (No Enable Hierarchy Integration option), 6000.3.7f1, 6000.4.0a3, 6000.4.0b7 (Element settings are not displayed in Editor Inspector)

Reproduced on: macOS Sequoia 26.2 (M4)