map boss skill points missing 2

I have completed all objectives and the pinnacle of flame quest but i am still short 2 points. I tried T16 6 mod in an irradiated/corrupted area, irradiated area, and corrupted nexus. I have even tried t116 6 mod in a irradiated with tablets to raise the level and nothing drops. I wish the legend would act as a check list but this feels like a bug.

TL;DR

I tried 6 mod t16 in all forms and cant get the last book to drop and the arbiter quest was completed.

EDIT: GGG please give more helpful wording for anomaly map boss as i treated it as corrupted nexus.

Isn't last 2 points come from Citadel T15-T16s with maxed mods?