How to reproduce:
1. Open the attached project "BugReproduce.zip"
2. Open Window>Animation>Animation
3. Select "thing" in the Hierarchy window
4. Change Animation to "anotherone1" in the Animation window
5. Rename "anotherone1.anim" to "anotherone2.anim" in the Project window
6. Click on the Animation dropdown in the Animation window
Expected results: Dropdown opens
Actual results: Dropdown doesn't open
Reproducible with: 2021.3.36f1, 2022.3.21f1, 2023.2.13f1, 2023.3.0b10
Reproducible on: Windows 10 22H2
Not reproducible on: No other environment tested