As far as i know, Stygian armorer III (at least the one i tested) can craft Derketo dancer outfit. So try to catch one. Also that armorer can make stygian noble (easier version of setite armor)
During the Purge if you’re lucky enough to find them or keep on capturing Armorers until the recipe shows up but yeah it could be a bug too. Only way to know for sure is to keep trying.
I’m reasonably sure that Zoara of the Marshes (who can be found in Sepermeru) can also craft that outfit - but as @syx said, it’s just a combination of Setite and Zamoran dancer outfit models.