Reproduction steps:
1. Open the attached “BugRepro” project
2. Open the “SampleScene” Scene
3. Select the “DefaultHumanoid” GO in the Hierarchy window
4. Move the “Timer” slider under the “NewBehaviourScript” component in the Inspector window
5. Open the Timeline window (Window > Sequencing > Timeline)
6. Select the “PlayableDirector” GO in the Hierarchy window
7. Change the current frame by sliding in the Timeline window
8. Reimport the “NewBehaviourScript” script in the Project window
9. Repeat steps 3-4
10. Observe the Game View

Expected result: The animation starts playing
Actual result: The animation is not being played and the “DefaultHumanoid” is stuck in the “T Pose” animation

Reproducible with: 1.7.0 (2021.3.32f1), 1.8.0 (2022.3.14f1), 1.8.6 (2023.2.1f1, 2023.3.0a15)

Reproducible on: Windows 10
Not reproducible on: No other environment tested

Note:
- After closing and re-opening the project, the issue gets fixed