Hello
I think I understand your problem. As a solution, you may first need to recheck the key assignments. In particular, it is possible that the truck axle and the trailer axle are confused. However, if the problem still persists after making sure that your assignments are correct, you can try deleting TruckersMp from your computer and reinstalling it.
I hope I can help solve the problem.
I wish you a good day.
Kind Regards
ESER 58
TruckersMP Veteran Driver II