Reproduction steps:
1. Open the attached “repro_IN-99239“ project
2. Open the “Assets/Scenes/SampleScene.unity“ Scene
3. Enter the Play Mode
4. Observe the crash

Reproducible with: 2022.3.61f1, 6000.0.48f1, 6000.1.1f1, 6000.2.0a10
Couldn’t test with: 2022.1.0a1-2022.2.0a15 - Unresolvable Animancer package errors

Reproducible on: Windows 10 (22H2), Windows 11 (24H2) (user’s), macOS Sequoia 15.3 (M2 Ultra)
Not reproducible on: No other environments tested

Notes:

* Reproducible in Player
* Not reproducible without the Animancer Pro v8 package ([https://assetstore.unity.com/packages/tools/animation/animancer-pro-v8-293522|https://assetstore.unity.com/packages/tools/animation/animancer-pro-v8-293522])

First few lines of the stack trace:
0x00007FFFED2F6515 (Unity) mecanim::animation::TransformValuesFromClip
0x00007FFFED2BF489 (Unity) AnimationClipPlayable::ProcessAnimationRootMotionPass
0x00007FFFED2C0435 (Unity) AnimationClipPlayable::ProcessRootMotion
0x00007FFFED2BE97F (Unity) AnimationClipPlayable::ProcessAnimation
0x00007FFFED2BDF18 (Unity) AnimationMixerPlayable::MixerProcess