I actually had this bug as well and might be able to help – the way it happened to me was I completely dismantled an RV and then rebuilt it, I think without actually starting a new vehicle, just using the old single-tile frame. When I rebuilt it (20 tile wide crawling castle), it would pretend to drive, I could turn the vehicle according to the new crosshair, but it wasn’t actually moving at all.
When I rebuilt it from scratch it drove fine.