How to reproduce:
1. Open the attached project “RMBElementBug.zip“
2. Open Scene “SampleScene“ (Assets/Scenes)
3. Select the “Directional Light“ GameObject
4. In the Inspector, right click on an Element of the Values array and press “Duplicate Array Element“
Expected result: The element which was right clicked is duplicated
Actual result: The element which was right clicked is not duplicated
Reproducible with: 2020.3.26f1, 2021.2.0a10, 2021.3.15f1, 2022.1.24f1
Not reproducible with: 2020.3.27f1, 2020.3.42f1, 2021.2.0a9, 2022.2.1f1, 2023.1.0a23
Reproduced on: macOS 13.0.1 (Intel)
Note: Nothing happens when trying to duplicate with RMB and there is no selection of any element