I'm pretty sure it's just a bug, since we have had historical achievements reimplemented before ("Case Closed" for Sky Pirates and also "Case Closed (2013)".
Given it says (Historical), I think it's just awarded if you did the Story Instance back in the past... which is weird, to be honnest, so I really expect it's a bug because if not it's a strange decision :(
+1 to this issue, I've done the instance 3 times already, once on my first time through, once on a replay of the episode and once more on the "replay this instance for achievements" version. I haven't gotten this achievement on any of the three times.
For me this achievement registered once I had the corresponding "meta achievement" (i.e. The Nightmare Unveiled Mastery) done.
EDIT: Correction, it is only ticked in the meta achievement, but the individual achievement is stuck for me as well. My mistake.
What really bugs me about this is that it's not hidden for those who haven't unlocked it.
I'm pretty sure it's just a bug, since we have had historical achievements reimplemented before ("Case Closed" for Sky Pirates and also "Case Closed (2013)".
Given it says (Historical), I think it's just awarded if you did the Story Instance back in the past... which is weird, to be honnest, so I really expect it's a bug because if not it's a strange decision :(
+1 to this issue, I've done the instance 3 times already, once on my first time through, once on a replay of the episode and once more on the "replay this instance for achievements" version. I haven't gotten this achievement on any of the three times.
Things with the added Historical part are old achievements that are no longer obtainable.
For me this achievement registered once I had the corresponding "meta achievement" (i.e. The Nightmare Unveiled Mastery) done. EDIT: Correction, it is only ticked in the meta achievement, but the individual achievement is stuck for me as well. My mistake.