In some scenarios you are asked to leave the cab, so you press Y to get off the seat and you are stuck, you cannot move. The only thing that has worked for me is to press the Map button, but even that is a little hit and miss.
Make sure you haven't accidently clicked down on the right thumb stick, this prevents moving when you get up.
This happens all the time and I am careful not to touch right stick. Surprised it’s not raised more often as a bug. Similar to Miles Platting which needs to be sorted too