Cannot add a UI Document into the Hierarchy when adding from Library in the UI Builder window

Steps to reproduce:

1. Create a new Unity project using the Universal 3D template
2. Create a new UI Document (Assets > Create > UI Toolkit > UI Document)
3. Duplicate the newly created UI Document
4. Open the created UI Document in step 2 to open the UI Builder window
5. Switch the Library view to "Project" in the UI Builder
6. Open the Assets foldout in the Library
7. Add the duplicated UI Document Template into the Hierarchy
8. Close the UI Builder window without saving and Discard the changes
9. Repeat steps 2, 3, 4, 5, 6, 7
10. Observe the UI Builder window

Actual results: The UI Document is not added into the Hierarchy

Expected results: The UI Document is added into the Hierarchy

Reproducible with versions: 2023.3.0a12, 6000.0.74f1, 6000.3.14f1, 6000.4.5f1, 6000.5.0b6, 6000.6.0a4

Not reproducible with versions: 2023.3.0a11

Tested on (OS): MacOS Silicon Tahoe 26.3