Missing Corrupted Nexus Quest

I'm level 94 and can no longer obtain atlas skill books from completing corrupted nexus quest. The quest is missing from the quest log. I've completed 4 corrupted nexus (no deaths) and not one atlas skill book has dropped. I'm fairly new to endgame mapping. I this a bug, or working as intended?

Edit: I have only 22 atlas skill points allocated to the atlas tree.