I'd like to do this edit that you're speaking of, but I'm unsure of what editor your refrencing and also what exactly you did in the image that fixed it
Viewing post in FS25 Railroad Rolling Stock comments
It's the giants editor available from giants software GDN. The i3d files of the carriages can be edited and the exactFillRootNode you can see with the arrow I drew on the left needs to have the rigid body collision filter group / mask changed in the menu on the right, in the new editor you can just click on the preset and find the exact fill node there and it will pre-fill the hex for you. (if image is hard to see right click and open in new tab)