Reproduction steps:
1. Open the attached “BugRepro” project
2. Open the “Assets/LayerMixerIssue/Scenes/Spawner” Scene
3. Enter Play Mode
4. In the Game View, press the “React Timeline“ button
5. Observe the character
Expected result: The character’s Rig remains intact
Actual result: The character’s Rig is mangled/deformed
Reproducible with: 2021.3.39f1, 2022.3.33f1, 6000.0.6f1
Reproducible on: Windows 10, Windows 11
Not reproducible on: No other environment tested