2nd player not taking any damage

[Mince]

Hello, does anyone know why the 2nd player in my match is not taking any damage? I'm the host and I take damage and die like normal. He's stuck at 100 health and jumped down the mineshaft in Ravenholm and didn't die. Cheats are off. I have a lot of experience with commands and such, but can't figure out what's causing this.

[v13]

Having the same issue