Skins Stuck With Slim Arms

I recently left the 1.11 beta. I had to reinstall Minecraft, but when I opened it, my custom skin had slim arms. I re-selected it to change my arm size, but both arm-size options were slim. I selected the slim option where the full-size arms usually are, but I still had slim. I repeated this process, this time selecting the original slim arms, but I'm still stuck with slim arms.

 

What I expected to happen was...:

There should be a full-sized arm model where the second slim-arm model is.

 

What actually happened was...:

The only available options are two slim-armed models. I can no longer make my arms full-sized.

 

Steps to Reproduce:

1. Open the Skins menu and select your custom skin.

2. Tap "Choose new skin" and select your skin.

3. When it asks me to choose my arm size, a second slim-arm model replaces the full-sized arm size.