Hi,
I’m having the same issue.
It’s not a solution for the problem but I found that if you keep scrubbing and set your “in” and “out” without releasing the mouse button the playhead won’t wander. It’s the only way to work without losing your mind with the crazy playhead behavior.
I was also wondering if this has anything to do with the “MagicPrefs” app I have installed to make the trackpad and magic mouse quicker. Does anyone have this app installed?
Cheers