thanks for reporting this issue.
Can you contact the support directly with the following information:
- Your operating system
- The kind of scene / character you are using
Ideally, a MOSK file to reproduce the bug would be highly helpful.
Sorry for the inconvenience.
Often, when I undo actions, the model detaches from itself, leaving some of the model in the last known position, and some of the model in the previous position (following the undo). In some cases, I've had it crash on me when I redo.