Are treasure maps broken on the snapshots. I have tried a few and am not finding the treasure
they've been working for me.
I would say try 3. I've not-found (and Dug /Mined everywhere, and /or used Spectator Mode, to triple-check) 2-3 Chests, total (if out of dozens).
So it may be hard to answer about the Snapshot. But that's - apparently - how it was Before (in 1.13 Aquatic Update).