In a multiplayer game, if a player who is driving a vehicle suffers a crash, power failure or other non-standard termination of the game process, all passengers in the vehicle become trapped inside unable to leave until the disconnected player times out.
The rest of the game continues along around the players, and they are still vulnerable to attack.
Have multiple players mount a vehicle. Have the driver force close Arma 3 via task manager or other mean.
Please let us know in note section if you are still able to reproduce this issue in latest Developement build.
Closing due to lack of feedback. If this issue is still reproducable for you, please create a new ticket for it or ask for this one to be re-opened.