I still cannot get the supplier achievement?

I have just collected my last ingredient for the supplier achievement ( I can't remember what it is called, but is a single item, found in the final chapter in a mission for Merrill, in prides end). I have used the black emporium to gain items before, but I have heard that this is not a problem anymore apparently. Is there a particular reason this wont work? I have a save just before I enter Prides End and collect it, if that can help?