Won't load characters in multilayer and red exclamation mark

When I'm in multiplayer i can see myself as my character (different version and personalised versions of Steve and the others), but for the person I'm playing with they don't see it, only the original skins. I've tried to go on and off and see what it could be, but the only hint I've got is when I go to play there's a red exclamation mark on my account before it loads. I have no clue how to fix it and it's getting frustrating