Just trying to place one of the robotic parts in symmetry mode always does this. IIRC the mod worked properly at least a few revisions ago, but I haven't been able to test them myself yet to see which one. Included is just a little craft I threw together. It has one rotatron set to symmetry. You can see one of them is on the craft, and the "mirrored" one is in front and above the cockpit a fair bit. If you move the primary one, the mirrored part moves "properly", but it's acting like there's some weird offset or something. Hope this helps before I head off for the night!
https://drive.google.com/file/d/1_ZB9M7c9EnACAf0PHkbjL2kF5xPldYLn/view?usp=sharing
