If you're in multiplayer, and someone else had moved the bus, then there's a fix on the way in the upcoming version 1.3.2. In the meantime, the bug is triggered by getting into the driver's seat directly from the interior, and then driving away... the code to update the interior's exit point doesn't start up if you do that in 1.3.1. If you switch seats to the driver's seat, or enter the vehicle from the driver side door, it will start to update the exit position correctly again.