Steps to reproduce:

1. Create a new project using Universal 3D template
2. In Project Settings > UI Toolkit, enable "Enable Hierarchy Integration"
3. In Preferences > General, enable "Use new Hierarchy window"
4. In the Hierarchy, right-click > UI Toolkit > Panel Renderer
5. In the Inspector, click "New" in the "Panel Renderer" Component and open it in UI Builder
6. Add a "List View" element to UI Builder Hierarchy
7. Save and Close UI Builder
8. In the Hierarchy, fully expand the "Panel Renderer" GameObject
9. Right-click on the "NewUXMLTemplate.uxml" or any other child GO
10. Observe the Console

Actual results: "Exception: The visual element must be part of a VisualTreeAsset to create a reference." errors when clicking on .uxml GO, and "Can not reference a temporary element  (ScrollView)." warnings when clicking on child GOs

Expected results: No errors or warnings

Reproducible with versions: 6000.6.0a1

Not reproducible with versions: 6000.3.11f1, 6000.4.0f1, 6000.5.0a9

Tested on (OS): Windows 11