That one is still missing. I only have Tower of Babil left to do on the map and still have 18.
So, if I go into the Tower of Babil, I'll get 19 again.
-___- No clue where did I miss that last one.
I was hoping it'll be in the Elemental Abyss but I cannot find a page there. But since we cannot get back in it ever again, I don't think it'll be there.