Ok,
I have levelled several characters through the Pandaria remix with the goal of securing the Quintessential Quintet achievement.
I did this before the pre-patch event hit, but after having 5 different classes levelled up, no achievement was checked off.
I assumed it would trigger when the Remix event ended, but alas, again no achievement.
Since the achievement only states “reach Max level on 5 different classes” I would have assumed that when I did reach max level on 5 different classes (6 chars, but 1 double) I just needed to do it during the same expansion.
Apparently there is an extra hidden requirement for the achievement that I have to reach level 80 (despite not being able to do so when I fulfiled the not hidden requirements of the achievement).
Not only was I dismissed by the service desk as “tough luck, we are too busy to deal with you”, but the achievement has not been rewarded still.
If there is a requirement to be level 80, just mention it on the achevement.
Regardless of that requirement, I should have gotten the achievement before that was even a thing.
Poor communicatioin on behalf of the devs and totally not happy that I have just wasted my time levelling up characters in the remix to get nothing out of it.