Possible fossils bug?

I'm on my fourth year of the game, and have found every fossil apart from the mammoth skull.

I've collected a batch of 20 mysterious nodes and 4 small nodes to get analysed at the lab, and have been going there first thing in the morning (after hitting the fossil pit) and resetting if I don't get the mammoth skull. I've reset easily 10 times now (I was counting, but I lost track), and still no skull. Is it worth raising a bug report? Has anyone else encountered anything similar? The drop rates make it improbable that I wouldn't have got it by now, although not impossible.

Playing on steam deck, v.1.1-1225, if it matters.