Hi everyone,
Please have a look at: https://playground.babylonjs.com/#K1QFZD#8
Expected behaviour: animal is somewhere mid clapping animation
Actual behaviour: animal back to rest pose
N.B. if you comment testAnim.stop(); it does not go back to rest 
FYI: On my end, the playground takes like 30sec to load. The scene clear color should turn red if everything is done.
Best wishes
Joe
Hi @Joe_Kerr — thanks for the clear repro!
Confirmed engine bug. AnimatorAvatar.retargetAnimationGroup was internally returning every avatar skeleton to its rest pose (in _computeBoneWorldMatrices, and again in _resetStates when fixRootPosition / fixGroundReference run). While testAnim was playing those resets were overwritten every frame, but the moment you called testAnim.stop() nothing was driving the bones anymore so the rest pose became visible — hence the snap to T-pose. The bug repros regardless of the fixRootPosition / fixGroundReference flags, since _computeBoneWorldMatrices runs unconditionally.
Fix: Fix AnimatorAvatar.retargetAnimationGroup clobbering active animations by Popov72 · Pull Request #18450 · BabylonJS/Babylon.js · GitHub — captures the avatar’s bone state once at the top of retargetAnimationGroup and restores it once before returning, so the call no longer clobbers any animation already playing on the avatar.