Ran into an issue where I spawned within the vehicle spawn in the Fortress. It did not permit me to pass through the barrier & it prevented the enemy team from being able to capture the Fortress as I was still being counted as being present. The only options I saw as a way out were to either kill myself via grenade, or wait for a vehicle to spawn that had a passenger seat.
I waited for someone to spawn a vehicle that I could hop into & it took me right out of the barrier without any issues.