Yeah, I've figured that already.
About five times it's happened, I might be a little vague with this as I don't have a good memory.
First was the Pool in Wall-Nut Hills, I was playing as the Commando Pea and I was defending the base. I died, and respawned before they took the base,and my character never appeared. They took the base, and as I was trying to move away, I was shot down by a Foot Soldier and was sent to the loading screen. The Zombies destroyed the Mansion before I was kicked from the game, and after the pre-match leaderboard, everything was fine in the next match. (Xbox 360)
Another time I was playing with a friend in G&G. We were playing on Main Street, and it was early on in the match, at the Apartments. I was playing as Zombies, as a Scientist. I was advancing on the base through the houses when I stepped on a Potato Mine. When I respawned, I didn't see my character. I didn't bother this time and just left the match. (Xbox One)
This happened again later on another match, on the same map. I was playing as a Tank Commander on the fourth objective. We took over the base, I was killed by a fleeing Chomper, and I respawned and didn't appear. Once again, I just left the match. (Xbox One)
It's more or less the same each time, just in the more recent ones I just left and had to apologise to my friends. Each time, I had been playing for at least 3 previous G&G matches in a row, wether they were short or long.