When doing a auto transition (for VTOL) in Mission mode, the waypoints are not followed. If the transition is not successful the aircraft will fly indefinitely rather than going to the next waypoint. The only way to prevent the aircraft from flying away is to manually abort the mission.
It also means that if setpoint is inaccurate for any reason the aircraft will transition in the wrong direction, only correcting to the target waypoint once the FW mode has been reached.