Nothing happens when try to select Thin Arm character variations

When attempting to select the thinner arm variations, nothing happens. Even after selecting the Alex model first, when you go to the size tab and select the thinner arm it does not select it or apply it. You can still click on it, but it doesn't apply or select it. I can still change the height, and I also have 2 out of 5 outfits that DO have thin arms. But when attempting to use the other three, or create a new skin it will not allow me to change from classic arm to slim.