1. Wear this avatar in VR with 3pt: avtr_b504b4b9-db85-467f-bc81-e7a10ede8c8f
  2. Open the action menu and turn on flight.
  3. Move your head up and down (Y).
  4. Observe that the hip and neck crumple strangely. (this does not happen on live).
I have also seen this affect the default locomotion falling animations on some avatars.