The bug

I've completed a Daily Trial Level III, Underhalls, using the Unique version of the Emerald Armor, the Opulent Armor, but I did not earn the achievement "Dress for Success".

How to replicate:

1. Obtain the Opulent Armor

2. Start a Daily Trial Level III with the Opulent Armor equipped

3. Complete the Daily Trial Level III

You should be earning the achievement "Dress for Success."
What happens is you don't unlock the achievement "Dress for Success."