Boss skillbook not dropping

Xbox series X


After patch 0.2.0f (no hotfixes)


Beat a boss on T16 Irradiated cleansed map. Have all points spent on atlas boss skill tree. Boss did not drop a skillbook to give me more points. I was doing it in multiplayer, but it was on my atlas using my map. The boss I fought was that one that's kind of like the act 2 boss, but with way less mechanics.