How to reproduce:
1. Open the user's attached project
2. In the Project window, open Timeline asset
3. Select the SpawningClip clip (observe the handles appear in the Scene view)
4. Deselect the ScpawningClip clip (observe the handles disappear)
5. In the Inspector window, select Recompile
6. Observe that the clip is deselected and the handles are visible
7. Select the SpawningClip clip (observe that the handles get darker)
8. Deselect the SpawningClip clip

Expected result: Handles are not visible
Actual result: Handles are visible

Reproducible with: 2019.4.26f1, 2020.3.8f1, 2021.1.6f1, 2021.2.0a17
Could not test with: 2018.4.35f1 (could not downgrade)

Note: The handles only disappear after restarting the Editor