Dragon Age Inquisition - Achievement for Dragons' Bane not Completing

I just recent finished playing the game and realized that although the game says that I've finished killing all of the dragons I never got the achievement for doing so. I'd really rather not go back to a previous save and have to do everything all over again. Has anyone else found another way to fix it? I've tried just playing a little more to see if it pops up but nada.