Kingdoms of Amalur: Re-Reckoning

This achievement should unlock immediately after you unlock your 61st achievement in the game. There is a rare glitch that has affected two TA gamers that I know of as of this writing. One was able to remedy the glitch, the other, till now, has not.

Recommendation: If you want to mitigate against this very rare glitch, avoid getting achievements outside your main save file. For the 360 version of the game, it was a popular approach to make a save and unlock achievements like Jailbreak, Out of Your League, Master of the Forge, Diamond in the Rough, Romancing the Gem, and the like. Following the achievements popping, the gamers would then revert to the save file made before earning the achievement. In the XBox One Re-Reckoning version of the game, this approach may contribute to triggering the achievement's glitch. Accordingly, try, as much as possible, to include all achievements in your current save file. The only exception should be I Regret Nothing. Since this achievement requires you to die, unless you unlock it as your 61st achievement, you will have to revert to a save made before plummeting to your death.

29 July 2022 Edit: @Metalhat1973 in the comments observes you must unlock all base game achievements under hard difficulty for Perfectionist to pop. I have no personal knowledge. Nevertheless, the walkthrough has the entire game played under hard difficulty and this is my recommendation.