This issue involves a base model with a built-in collar that is "fused" and made invisible by setting the scale to 0,0,0. To make the collar visible again, an animation is played to change the scale back to 1,1,1. The collar has a root part that represents the actual collar, and physbone components that enable it to dangle around the neck/chest. In the beta version, when the collar is scaled from 0,0,0 to 1,1,1, the physbone components ("Tag" part) disappear and are nowhere to be seen on the model, causing unexpected behavior.
To replicate this issue, follow these steps:
  1. Create a base model with a Collar and a root part.
  2. Add physbone components to the collar for movement.
  3. Set the scale of the collar to 0,0,0 to make it invisible.
  4. Play an animation to change the scale back to 1,1,1 to enable the Collar.
  5. Observe that the "Tag" part of the collar with physbones is now missing and not visible on the model after upload.