I was testing an avatar as I was updating it by having 2 instances open using a world testing instance when I noticed my clone's physbones were acting inconsistently.

I went to that client to see if changing the avatar would work, which changed the avatar on both due to VRChat's recent update to real time avatar swapping. When I did, the other avatar's physbones didn't work.

Resetting the avatar one the instance where the physbones are broken swaps which avatar has functioning physbones as well.

Edit: upon further testing, this happens when physbones initialize. Toggling a physbone component to inactive on one instance's avatar, then active on the other, results in the second avatar having that physbone component working correctly. But it still remains impossible in my testing to get any physbone component to work on both avatars simultaneously.

Unsure when else this may affect players, or if it can be recreated in other scenarios.

To recreate