docking through robotic parts causes bugs

[king of nowhere]

the title says most of it. i have this rover with a robotic extensible arm with a docking port in the end, but whenever i try to use it, the rover gets scrambled badly.

for reference, the rover is my "dancing porcupine", the second picture there highlights the robotic arm with which i am trying to couple (the trunk). And this image shows an example of what happens when coupling - though different situations give different bugs.

 

it's not a once-in-a-while occurrence. it always gives bugs on coupling, to the point that i cannot use it for its intended purpose.

and, granted, it's a complex rover, but i did have a previous version that was only marginally less complex, and this one can dock without bugging. sometimes.

what could i do to fix this?

(EDIT: so far, since i only wanted to transfer some fuel, i opened the saved game file and manually altered the resource values. but that's hardly an ideal solution)

Edited August 1, 2020 by king of nowhere