Can't gift any K/DA skins to a friend?

Not sure this is a bug--guess the help board isn't a thing anymore?

Anyway, long-time friend, both of us are high-level, and he owns every champ (literally no option to gift him a champion). I want to gift him the new Akali skin, but none of the K/DA skins are even showing up. Why wouldn't I be able to do this?

Thanks.