Im honestly not sure how to reproduce this reliably because it seems random., and seems to depend on the map. Some maps its fine, others it's not. Both newer, and older maps. Random.
But long story short, I have an avatar with a cloth skirt and cloth hair. it works fine.
The moment the avatar is uploaded with that, it seems to cause issues with cloth. Immediately what happens is the hair now stays still and does not move with my head, I can crouch and look up and see it floating there, and the skirt, it actually creates a DUPLICATE of my skirt, which similarly, ignores all movement. Both are still cloth, and that works, but both behave as if the model was standing still.
I should mention that all that is a local only thing. noone else sees it,
it does not show in the mirror either.
if i repeatedly reuploaded the model there was a chance it would work fine, and a chance it would not.
switching out of beta stopped the problem. But it does not seem to be Beta specific. Yet, it's way worse in beta. It happens way more often.
I checked scale, made sure armature was 1/1/1, removed any constraints, nothing changes this. Happens both in vr, and in desktop.
I took a video to show what I mean
EDIT: I did some testing by visiting several maps and noting the date they were last updated, and found this is reliably reproducible in any map made/updated before late September, though september itself has a 50/50 shot of working. Only fly in that ointment is that my homeworld was updated april yet works fine. So it's an outlier.
EDIT2: I updated a map of mine to udon and sdk3 and it still retains this problem. SO Im not sure what to really make of it anymore if a map that is freshly updated has the issue. I guess map age doesnt actually matter.