This also happens with the M4, even if you just walk forward.

I was able to get out of the room by a ladder that was on the other side of the room.

Was able to test this several times tonight. What was found is if you are killed, so your player is dead, and the player exits the server, the player's body disappears. Did not test this on other servers to see if it was a server issue. For a while we thought it had to do with players being unconscious, because the same thing happens with an unconscious player, if they go down, they can disconnect and their body will disappear (Though we did find on numerous occasions that when this happened your character automatically died.)