Reproduction steps:
1. Open the user's attached "AnimationEventBug" project
2. Click on Assets/xbot@idle (1).fbx in the Project window
3. In the Inspector window, in the Animation tab, add an Event
4. Try changing Root Transform Position (Y) Based Upon setting in the Animation tab

Expected result: The value changes
Actual result: The value stays the same

Reproduces on: 2018.4.30f1, 2019.4.18f1, 2020.1.17f1, 2020.2.2f1, 2021.1.0b2, 2021.2.0a1

Notes:
- The issue also reproduces when writing a value or checking/unchecking a checkbox in the Animation tab
- Clicking Apply does not resolve the issue