In order to get the Subtle Hidden Artifact appearance, ya gotta get some Keys to the Palace of Lei Shen. One is supposed to get these from an item in the Uncrowned Vault in the Rogue Class Hall. In order to loot the Keys, you have to turn in a Marrin Coin to Marin Noggenfogger. This is supposed to let you see the lootable object [Sparkling Set of Keys] https://www.wowhead.com/object=252282/sparkling-set-of-keys
I have turned in 30+ coins to Marin, and have never once seen the the Sparkling Set of Keys. I only see the lootable sticky bombs, fake coins, thistle tea. I have seen the Smoke Powder, but that was a few times, and only at the beginning of my farming. Is there a bug? Does the SSoK no longer spawn?