I am missing a skin for widowmaker that I got from my origin box and I have no idea when it happened since last I played was before the ow2 swap. I think It was call Noire it was the one where she had the long tube like hair and the metal bits at the end. I still have my box somewhere in storage, but I have no idea if I kept the code for that specific skin.
Assuming you did in fact redeem the code and she was added into your account back in the day, I also had this same issue with the Noire skin. She wasn’t listed in my normal owned skins, but I was able to make her appear by doing a hero gallery search for “Special” (the one with the Blizzard B logo) under “Category”. Good luck!
I just checked and I too am missing this skin- but originally had it definitely
I just looked like you suggested and found it!