I've done all the 16-man ops possible pre 2.0 and even seen them in my codex, but after checking achievements it says I haven't and when I went to check Codex they had all mysteriously vanished. I have "Timed Expolsive" from beating Nightmare EC in under two hours but it was from doing it in a 16-man group. I want to get as many achievements as I can but putting together 16-man Nightmare runs isnt very easy, I would know because I'VE ALREADY long ago and DO NOT want to do it again please. I have logs, fights were recorded and can probably round up 15 or so witnesses. Could I get an answer about if it's something that was over looked or is it just something we all have to do twice for it to count?

 

http://www.torparse.com/a/123815 (16-man successful Nightmare EC title run 06FEB13)

welcome to the broken achievements. At least its possible to redo these ones. Last night on a whim my guild joined a pug and did 16m nightmare kp. Turns out it gives you the achievement for not only nightmare 16 but hard mode as well.