Reproduction steps:
1. Open the attached “BugRepro” project
2. Open the “Assets/Doc.uxml” file
3. Drag the “Template_B” into the “Template_A” in the Hierarchy pane
4. Save the document (Ctrl/CMD + S)
5. Obersve the Console window

Expected result: No errors are thrown
Actual result: “Element 'AttributeOverrides' is missing a UxmlElementAttribute and has no registered factory method. Please ensure that you have the correct namespace imported.” error is thrown

Reproducible with: 2023.2.10f1, 6000.0.4f1
Not reproducible with: 2021.3.38f1, 2022.3.30f1, 2023.2.9f1

Reproducible on: Windows 11
Not reproducible on: No other environment tested