How to reproduce:
1. Open the attached project "Orbital"
2. Open the "SampleScene" scene and select the "Third person Aim Camera" GameObject in the Hierarchy
3. In the Inspector, under the "Cinemachine Orbital Follow", change the "Vertical Axis" to any value
4. Click Undo (Command + Z)
5. Click on the "Vertical Axis" field name and observe the results
Expected results: The field doesn't disappear
Actual results: The field disappears
Reproducible with: 3.0.1, 3.1.6 (6000.6.0a5), 6.6.0 (6000.6.0a6)
Reproducible on: macOS Tahoe 26 (M1)
Not reproducible on: No other environment tested