I got a buried treasure map from a desert temple, and there is no marker on the map. I searched underground in spectator mode, but didn't see a chest anywhere on the map.

Was this ever resolved? I have the same issue

I forgot about this issue. Some later analysis showed that the marker is right on the edge of the map, which prevents it from rendering. I ended up using a JEI addon that puts item NBT on the tooltip to check the location on these.