What I expected to happen was...:
When I find a shipwreck or ocean ruin chest, it contains a buried treasure map that leads to a buried treasure.

What actually happened was...:
The buried treasure map is just a renamed regular map, without an X or anything indicating the direction to go. This seems to be random, but none of the 6 maps I've found in my single-player world have led to treasure.

Steps to Reproduce:
1. Open a new single player world.
2. Find the nearest shipwreck/ocean ruins and find a chest in there containing a buried treasure map.
3. If that one works, travel to the next one and repeat.