Fundamental Fossil Drop Issue (Delve breakable wall)

For some reason, fundamental fossils have a cap of 2 fossils being dropped when opened behind a breakable wall. Even if you're on depth 500 and the other fossils drop 6 at a time, this one is always 2. However, if you open a vein in the darkness, but not behind a wall, more can drop. I have seen up to 6 dropping this way. I am assuming the wall should function like other fossils where its possible to drop more than 2 here.