As the title suggests, we have likely found out why Av3 avatars currently break!
So locally no matter the tracking type most things work completely fine apart from some people sliding forward when doing an animation, whereafter the body then snaps into place (also related)
When the 3.0 user is in desktop mode, all their animations (facial expressions, toggles, dances) work completely fine to everyone who sees them
When the 3.0 user is in regular VR mode, facial expressions and toggles work fine but root motion on dances seems to stop working
In fullbody facial expressions and toggles dont appear to the spectator anymore and all dances turn to T-Pose, yet generic transforms like rotation of the entire avatar still work fine
Other people have reported their avatars getting stuck after an animation or having to play an animation to not be stuck in a pose anymore
All the previously explained issues can be explained by one single component of the av3 system: The tracking control component
Tracking control malfunctioning would explain people getting stuck in animations, sliding at the start of an animation until the avatar snaps into place and even everything working fine in desktop as the tracking control is nearly always on animations anyways as opposed to fullbody.
We tested this in a group of 3 where we had 2 people spectate and the other switching between tracking types. We also found some issues with avatars breaking when loading into the world with them as opposed to changing in the instance which also relates to tracking control in a way.
Before I finish off this post id also like to refer to av3 avatars sending out countless missing object and script warnings in the logs such as PipelineSaver, CustomAvatar and Prefab-ID-
Hope this helps fixing the current issues