Everyone turns into Steve

The other day me and my friends were playing and they were Steve 3 minutes after joining the game. They hadn't changed their skin because it would have said in the chat. So today me and my Girlfriend are playing together and her skin also turns into steve 3 minutes after joining the world. I told her to stay still for a bit and we both saw as her skin changed to steve on its own. It apparently happens with my skin too but changes back right away. Please fix this it's getting rather irritating.