To explain this issue in a bit more detail i need to give some context.
The world this issue was discovered on was on a server hosted by a 3rd-party server provider.
Many hours into gameplay i decided to move far away from spawn, and travelled to around -4000Z in the nether and found a village to setup a base in.
After many hours of gameplay i managed to create a cartographers table, and even get a Villager with the Cartographer profession.
When leveling this Villager to Journeyman, something went wrong, and the world had a massive lag spike. After this, everything seemed like normal, and i was now able to trade for a Woodlands Explorers Map.
After purchasing the map i decided to travel to the nether to gather some ore, however, when entering the game was loading much longer than usual, and when it finished everything i had dug out in the nether was gone. Travelling back to the Overworld was to a bigger shock; The village had reset, and all my items were gone.
After looking in the server console i noticed the error messages provided in the first photo below.
Loading a Vanilla server on my own computer did not cause this exact issue, but it caused major lag spikes (see picture).
I am yet to try to reproduce this issue on fresh Singleplayer worlds, but this could be a major bug with cartographers, or maps in general. If a server auto-saves at the wrong time then this could possibly risk a loss of all world data.
The world-file where i have managed to find this issue can be found here.
NOTE! It's over half a gigabyte!
I have a save of the world before the issue occurs, and i am able to re-produce it by following these steps:
- Trade with the Cartographer to make him level up to Journeyman (seems to take 1 trade)
- Wait until the lag spike finishes
- Trade with the Villager for the map
- Put the map in an item frame, close to the other map in the house (see second picture)
- Travel to the nether
I have not been able to fully re-create the issue in Singleplayer, as force-crashing the game after entering the nether seems to fully load the chunks, so this might be a server-side only issue. Hopefully this will help with finding the root of the issue.
NOTE: In case loading the world in Singeplayer/Multiplayer with a different account, the co-ordinates for the village in question is X=-747, Y=65, Z=-32140