Mouse glitching when entering mouselook

I'm still having a bug with mouselook that I can't find anyone anywhere complaining about. Hoping someone has insight:

If I hold right click to begin mouselook, everything is OK as long as my mouse wasn't moving at the time.

If my mouse is in motion when I begin holding right click, then the camera will jump uncontrollably to the side or behind me. I think the issue is that it's trying to center the mouse before doing mouselook but due to a bug, ends up moving the camera's position as well. But nobody else complains about this so I'm suspecting my setup somehow. I've tried different mice, etc. to no avail.

This is super frustrating.  Does anyone have any ideas here?