Changes are not saved when changing Styles' orders in the UI Builder

Reproduction steps:
1. Open the attached “ASDQWE” project
2. Open the “Assets/test-doc.uxml” asset in UI Builder
3. In the StyleSheets tab, change the order of the two styles
4. Save the changes and close the UI Builder Window
5. Repeat the 2nd step and observe the position of the styles

Expected result: The styles' orders remain changed
Actual result: The styles are ordered as if no changes were made

Reproducible with: 2021.3.26f1, 2022.3.1f1, 2023.1.0b19, 2023.2.0a17
Could not test with: 2020.3.48f1 (UI Builder is not available for this version)

Reproducible on: Intel MacOS 13.3.1

Note: Opening the “Assets/test-doc.uxml” asset with an IDE displays the same results