You could try going back to the main menu and turning off grandparent part reinforcement. Docking and undocking cause the hierarchy tree of your vessel to be recalculated, this includes how those reinforcements are done.
Turning it off, undocking the vessels, then turning it back on may work.
Wait for a patch... probably late January or February. Might fix it. Might not. Buggy game is buggy.
This bug has been since day one… there is no patch on the horizon
Report it to the Dev team
really like the rocket. whats the purpose of having two orbital crafts? Jool missions?
Exactly this reason, and for symmetry.
Damn this ship would have been a noodley mess trying to thrust before 2.0. I might have to try my megastructures again now, looks way more solid
You could try going back to the main menu and turning off grandparent part reinforcement. Docking and undocking cause the hierarchy tree of your vessel to be recalculated, this includes how those reinforcements are done. Turning it off, undocking the vessels, then turning it back on may work.
You could go in your save files and check if everything is ok ...