My tiefling PC's tiefling tail seems to vanish when I use werewolf form. I shift back and there is no tail. I toggled the relevant cloak options and it stayed gone. I had to get a DM to take me back into the character changer room to get it re-applied, and then I went out and found a cure to my lycanthropy to ensure I can *keep* the tail (farewell, sweet wolf, I will miss you

).
Considering that the wings also obey similar mechanics for when they show and when they are hidden and how they are applied, I think this is likely an issue for other uses of these appendages toward the various forms of what used to constitute -polymorph.