Just tested this in the Dev build and it doesnt seem to be an issue, will look into it further as well
But here is what was happening

1. spawn core (do not change the default name)
2. add a rail docker to it
3. attempt to look and fly around

not really sure how to describe what happened besides that it seemed to rotate around the point that you were looking at and so when you turned it would accelerate you even if you didnt add any thrust. Another way to tell if this would happen is that there would be two rail dockers in the weapons menu even if you had only added one onto the core.

did you add the rail docker in the front and thus the center of mass became "off" to the raildocker in front of you, which is obviously see-through then?

Yes in front facing down and away from the core but it made it as if the center of mass was a few hundred meters away

oh, thats odd, however, if you get steps to reproduce please add, will keep this open for a few days

followed the steps, can't reproduce the issue with 0.19359

Same here, it also seems to have stopped in .19354, I will keep you guys posted as to if it happens in a dev build.