Now after further investigation I think it is an issue with the two new mutations. We just beat the brood-mother and I unlocked mom genes and she did not. Also, in her crafting menus the recipes for the club and mask don’t show either. I hope they fix it in the next patch.
I am playing a co-op game with another player. I am hosting the game and I was able to unlock mithridatism after killing my first 5 wolf spiders. My other player has now killed 20 spiders. We have tried killing them over multiple days, without dying, and all in the same day without dying.