Prismatic Greataxe Schematic

I understand that to acquire the prismatic greataxe schematic requires me to complete "Learn more about Dragons" war table operation but it is missing. I have completed Breeding Grounds quest at Emprise Du Lion and hunted all High Dragons and completed JoH and Descent. Why is the operation missing. Is it because I completed the main story before this quest? I also have Frederic part of the Inquisition too.