I think it would be a good idea to update the FAQ with a temporary solution to treasure map generation whilst MC-218156 isn't patched.

PaperMC/Paper#10536
https://bugs.mojang.com/browse/MC-218156

Issue: Buried treasure maps not generating.

Solution:
To fix, on paper servers

  treasure-maps:
    enabled: true
    find-already-discovered:
-      loot-tables: 'default'
+      loot-tables: 'false'
      villager-trade: false

The buried treasure map is generated by the server searching to find an unexplored/ungenerated buried treasure. This didn't work on my server, as all chunks are already pre generated / "explored" (by Chunky)
To fix this issue, I disabled the check the server does to see if the chest has already been looted (chunk generated). This was successful.

Thank you for the heads-up, wasn't aware of this one. I added a bit on it to the FAQ, please proof read and if there are any corrections needed let me know.