Multiplayer bug, LAN multiplayer. Players that joined my world had no names.

Players that joined my world had no names, and when using /tp /r /s the name of that player became entity.player.name . Without using /r, there is no way to teleport or even do any sort of commands to the player. The player's nametag also disappeared. I've double-checked & the player that joined my world actually has a player name. It just disappeared once they joined my world.