"Hints Completion" Achievement ?
Check the ? symbol at the top. Thats the “hints” menu and scroll down and see which one you haven’t learned yet. I know some of them you have to create other classes in order to see.
I’m in the same situation as you. I think the problem hint is related to the mesmer clone one. As this was the last one that I had to get, so I could see the 81/82 for a while before I played on my Mesmer.
Tbh I think if anything it is a bug and you may need to post in there. Good luck with it tho.
Since when did this business of being a hero become being a business?