Insane Difficulty: Strago not learning Lores (no status effect, etc) - Insane Difficulty

Been trying to get Aero in the WoR for a couple of hours, no luck. Even tried unequipping all gear/relics. What am I missing?! I've had it Sketched, I've waited for the monster to cast it (always group cast, does this matter?), Strago lives to the end of every fight with no debuffs... Is there only a % chance that he will learn it? Help

Aero, unfortunately, is no longer a Lore.

There is a list of Lores in the Printme

That's a relief! I was going crazy, thank you!