Reproduction steps:
1. Open the attached “New Unity Project.zip” project
2. Open the “UI Builder” (Window > UI Toolkit > UI Builder)
3. Add any element from the Library to the Hierarchy (e.g. “Label”)
4. Select the element and find the “StyleSheet” section in the Inspector
5. Unravel the “Matching Selectors” property
6. Copy any of the selectors by Right clicking and Copy

Expected result: The context menu for copying is shown, the Selector gets copied
Actual result: No context menu is shown and there is no way of copying the Selectors

Reproducible with: 2021.3.35f1, 2022.3.20f1, 2023.2.11f1, 2023.3.0b8

Reproducible on: Windows 11, macOS 14.1.1 (M1) (User reported)
Not reproducible on: no other environment tested