Thin arms(?) "Classic Skin" Character reverts back to thick arms every time the game restarts.

I use my classic skin with the thin arms option, and my skin is also made specifically to be used with that option, but every time I close the game and log back in, I see not only it has changed back to thick arms and is broken due to missing pixels from the thin arms skin file, it also has the cape unequipped with every log in.