Have been having the same issue, any vehicle with a native weapon e.g. Hunter GMG will not move at all when given a command. When a group starts outside the vehicle and the "get in" waypoint is given, the group leader will get into the vehicle and the rest of the group will return to formation. Normally unarmed vehicles e.g. Standard Hunter will move as intended but the issue with the Get In waypoint still exists. Finally when starting with a team already occupying a vehicle the group leader (regardless of the next waypoint) will immediately order that 1 or 2 soldiers disembark which makes no sense. The units do not respond to the order which causes the vehicle to remain stationary.