I found a treasure map and the map did not 100% match the world, as the chest was hidden below solid rock in the caves.
This has never happened to me before, so I am posting this as a possible bug
#Treasure Map shows chest below rock
frosty rain
This is the current save file and the correct location.
Island Name: "Land of Scorched Earth"
2 islands north of the starting island.
Funny thing, I posted about a different bug and uploaded my previous save file yesterday.
In this save file I did not get the chest yet, but I should already have the treasure map, so you should be able to easily reproduce my findings 😁