1 - Get in the editor (3D)
2 - Create an offroad (unarmed), driven by an AI on a road. Name it offroad
3 - Add a waypoint further down the road, don't edit it in any sort of way (medium speed)
4 - Add a player (I was a FIA - AT)
5 - In the player init field : this moveInCargo [offroad,4]
6 - Preview
7 - Wait for the offroad to gain some speed
8 - Shoot your RPG until you encounter this issue (don't spend more than 5 minutes trying, it did not took me that long)