I tried the Mod today, but i get a Empty Map? I can rightclick it & i get a map with the location im in right now? And the X is missing? ^^"

BuriedBarrels-1.18.1-1.0.3-fabric-release

Based on my tests, this seems to happen when the structure is located at the border of the map. This prevents exploration maps from rendering the red cross. I will check out if there's any way to fix it but I don't know for sure, since maps are being generated via loot tables, just like vanilla ones.

I think this is because barrels can spawn on chunk boundaries. Try to move barrels to chunk center or move on one block from boundaries if you generate it in random position in chunk.