Pachycephalosaurus animation/model issue

When resting at certain angles on the pachycephalosaurus when you stand up your leg will demorph. It occurred with me and one other friend of mine while we were playing on them. Most notably occurred while laying on a root in twisted forest. This occurred on official servers. Can be replicated on any slope however.

The right leg would twist into itself several times before correcting. Occurs on left leg as well depending on what slope you are laying or sitting down on. Has a higher chance occurring the steeper the slope.

The model will not demorph when standing back up from resting or sitting. when laying down completely the model may start to demorph while laying down but its more noticeable when standing back up.