As stated in the title, when a world is open to LAN and the guest player relogs, he/she loses all his/her items and advancements. Even dogs do not recognize their owner.
Comments 4
Could not reproduce; maybe she was in offline mode at first (skin wasn't working, she relogged to fix it).
Does the person logging in use the same Minecraft account as before, and is not or has not been using offline mode before?