Reproduction steps:
1. Open the attached project "ReproProj"
2. Open the “/Assets/Scenes/SampleScene.unity” Scene
3. Open UXML1.uxml
4. Select 'test-classname' and change height value to 250
5. Save file
6. Close UI Toolkit Editor
7. Open USS1.uss
8. Change the height value of 'test-classname' to 550
9. Save file
10. Open UXML1.uxml
11. Observe the value of height for 'test-classname'

Expected result: The height value has been updated to 550
Actual result: The height value is still 250

Reproducible with: 2023.2.0a19, 2023.2.0b12, 2023.3.0a8
Not reproducible with: 2021.3.31f1, 2022.3.10f1, 2023.1.16f1, 2023.2.0a18

Reproducible on: Windows 10 Enterprise 21H2
Not reproducible on: No other environment tested