I purchased the following cosmetic sets from Osidion in Dornagal: Lilac Educator’s Knowledge, Midnight Educator’s Knowledge. Each set includes two chest appearances: a Robe and a Vest.
I received the Robe appearance for each set, but not the Vest appearance. The Vest appearances are still marked as unknown for my collection.
I submitted a ticket to customer support about this issue, and they suggested a UI reset which did not resolve the issue.
Anyone else experiencing this?
I have been having the same issue with a few sets like that, the preview will show a vest options, but when you go to transmog it like that it will be a robe instead. The Delver’s Cloth Armor is another one that has this same problem.
I just logged in today and the issue seems to have resolved itself. The vest appearances are now in my collection and I can mog them. I haven’t done anything or changed anything since my OP. 
Perhaps come back tomorrow and see if it’s resolved, or put in a ticket?
This bug might have cropped up again since I do not have the Cobalt Educator’s Vest despite purchasing and using Cobalt Educator’s Knowledge.
I’m gonna see if the weekly reset tomorrow fixes it but logging out and back in, as well as fully exiting the game, does not unlock the vest transmog at this point in time.