I'm having this issue as well, build 213, and a clean 23.5. It's not just RCS in docking guidance, it's happening whenever MJ is trying to stay on a node (or docking), whether RCS is on or off. Both large and small vessles of mine can be seen oscillating when zoomed in. It seems to oscillate around the target, and cannot seem to stop on the target. I get the impression that it corrects to get on target, but fails to slow rate of turn until the target has passed, thereby pushing it into a perpetually correcting loop.