UITK Debugger new Classes element is not created with no information or warnings thrown when adding more than one element with the default name

Steps to reproduce:

1. Create a new Unity project using the Universal 3D template
2. Open UI Toolkit Debugger (Window > UI Toolkit > Debugger)
3. Click on the "Select a panel" dropdown and select "HierarchyWindow"
4. Open the "EditorPanelRootElement" foldout
5. Open the "VisualElement" foldout
6. Select the "Toolbar" element
7. Open the "Classes" foldout
8. Add a new element by pressing the "+" button
9. Repeat step 8
10. Observe the Classes list

Actual results: Second element is not added and no information or warnings are thrown

Expected results: Either an informational dialog or a warning is thrown, or the second class is created with an iterated name (for example newStyle 1)

 

Reproducible with versions: 6000.0.66f1, 6000.3.5f1, 6000.4.0b5, 6000.5.0a5

Tested on (OS): MacOS Silicon Tahoe 26.2