Steps to reproduce:
1. Create a new Unity project
2. In the Hierarchy, create any GameObject
3. Open the Animation window (Window -> Animation -> Animation)
4. With the GameObject selected, click "Create" in the Animation window
5. Click "Add Property" and add “Cube : Rotation” Property
6.Select “Curve” tab
7.Expand “Cube : Rotation” Property
8.Right-click in “Cube : Rotation” Property
9.Select Interpolation > Quaternion from the menu
10.Observe Rotation Property  

Actual results: After selecting Rotation Interpolation types, property collapses
Expected results: After selecting Rotation Interpolation type, property should stay expanded

Reproducible with versions: 6000.0.65f1, 6000.3.4f1, 6000.4.0b4, 6000.5.0a4

Tested on (OS): macOS Silicon Tahoe 26.2 (M1)