In the current experimental version, if I am using a mounted machine gun, whether it's in a vehicle or a gunner nest, I have had 4 occasions of getting shot and going unconscious and not being able to get back up after waking up. My vision comes back as if I'm no longer unconscious but my character is stuck on the ground in the unconscious animation, I can spin my camera but can't get up.
It seems this is replicated when another player removes my character from the gunner position in a vehicle or anytime when using the gunner nest. Also other players can not interact with my character to heal while in this state.
Current solution is to respawn.