On LAN Worlds, Guest player data fails to save properly. This only takes effect when the world is saved before the guest reconnects. Most of the time all data is wiped except maybe a couple of achievements.
MC-92540
LAN World Save Error
Resolved
Awaiting Response
0
Is this still an issue in the most recent versions (i.e. 1.10.2, or 16w42a) of Minecraft?