SOTFS(PC) - Lucatiel achievement didn't unlock.

So I just got Lucatiel's equipment at Aldia's keep, but the achievement didn't unlock, any ideas why?

I'm going for all the 100% achievements with DS2 being the last one I need to complete, a little annoying as I'm sure it will be much harder keeping her alive for the fights on NG+. Any possible solutions or tips?