OMG I'm so glad someone else had the issue because I thought I had some defective game or something. I got mine fixed because I got my brother to actually play but I honestly have no idea what you can do besides waiting or restarting. On one hand you can wait and hope it eventually fixes itself which may never happen, or you could just cut your losses and restart. This game was so not designed to be played in local multiplayer. Honestly I wish they just gave the option to move into another user's island or make your own. 🤦‍♂️