I wanted to transmog my Dracthyr to use the Blood Elf heritage transmog (Sin’Dorei), as the visage form is technically a Blood Elf. The set didn’t appear as an available set when I opened the transmog tab, which confused me. Is this a bug or is Dracthyr not supposed to use the Blood Elf heritage transmog?
I did some quick search but didn’t find anything on it other than wowhead stating that the heritage armor is part of the transmog sets eligible to Drachtyr…
Reason why you can’t do this is because it’s a Blood Elf Heritage Armor, not Dracthyr Heritage Armor. It’s only available to Blood Elves. Dracthyr male visage is based on Blood Elf model but it’s not a Blood Elf model and the acutal model doesn’t matter. What matters is the race, and race doesn’t change when you shapeshift.
It’s the same thing with Worgen heritage armor, when you change from worgen to human form you still can use that armor but you can’t use that armor if you play human. Hertiage armors are locked to one race only and can’t be used on any other race.