My friend cannot play minecraft on my realm.  I have multiple other members on the realm that can play, and he is the only one with this issue.  It does not say that he has joined the realm when he does, but his character appears.  He can't take damage, I can't /kill him, or teleport him, he doesn't even show up as an entity, he can't get in a boat, I've placed him in lava, and suffocated him in gravel.  He has an infinite loading screen, and we can't find anything that will fix this issue.  I've closed the realm and reopened it.  I've kicked him from the server, and blocked him, and he's rejoined with the same issue.  He has uninstalled minecraft, restarted his computer, and updated all of his drivers.  I need a fix as soon as possible please help.