Zombies bug/glitch after wave 8 my bullets are not registering

I would say they do no damage but that isn't even correct. The bullets don't even show 0 when they hit. Only explosions do damage so trip mine, ray gun etc. Even then I feel like the ray gun damage is only registering sometimes. Anyways, is this only me? If not how would I fix this? Another thing I noticed is that barriers ALWAYS repair by themselves with nobody near them. Am I just getting into lobbies with hackers or something?