Hello I'm a developer from the plugin ImageOnMap and I think I've found a bug that has been in spigot for many years. Many users from small server got an issue that I have been investigating recently, sometime for no apparent reason the world/data/idcounts.dat is not updated when restarting the server (and some maps have been generated so the count should be increased). This leads to many issues with the id count that became offset. (some maps in the world have an ID greater than the one in the idcount.dat). In our plugin we keep track of the given ID in order to track maps on which we replace the render, I write down the IDs of maps in a separate file that's how I know that idcounts was not properly updated .

Steps to reproduce: call Bukkit.createMap several time (the best is to do it 2000-4000 times to reproduce the issue) then stop the server brutally (by killing the task or doing a shut down and crossing fingers)

The issue is not common and tends to be linked to small server operated by people that are most likely to shut down there computer and not properly stopping the server