Yeah, this isn't working (just needs a quick fix and will hopefully get dealt with today).
If you found Aurous and didn't get the achievement, please submit a ticket and we'll add it to your account manually. :)
Goodgood! :)
This is being fixed RIGHT THIS SECOND, so future findings of this minion should award the achievement. Again, for those already affected, please file a ticket so we can give you the achievement manually.