[Shinja]

When player go ClassSelection from OnPlayerConnect, his vw will be 2, and when he spawn vw will be 0 so when he uses the command /changeteam, nothing changes his vw so he will at ClassSelection on vw 0, so he will see the vehicles those are created on vw 0, also players ect...

So the solution is to set vw again to 2 OnPlayerRequestClass or in your command (if it kill the player, and wont let him playing in vw 2)