TimelineAnimationPlayableAsset Memory Leak

Hello,
My project encounter memory leak.

I use assetbundle to load scene,and unload(True) assetbundle.
I want to delete every assets that loading from assetbundle when unload(True).

But there are some object can not be deleted,"UnityEngine.Timeline.AnimationPlayableAsset".
There are always rederenced by ManagedStaticReferences,I do not know what static reference.
I sure that my script does not reference AnimationPlayableAsset.

Do you have any good idea?

Thank you!