Thanks to a bug report from our users, we noticed that the achievement "to the end" ("Completed a game world by participating in it all the way to the last day, and played for a minimum time of 60 (real) days."
) was being assigned incorrectly. Basically the error was that the achievement was assigned to players who had player less than 60 days instead of more than 60 days ...
The issue has been fixed, and achievements for Jet Age #7 will be assigned shortly. Since the previous achievements of this class were assigned incorrectly, they have been removed from anyone who has already got one. (unfortunately we cannot check the data of any older game worlds for this badge since the data is not stored in long term)