Skin reverts to Steve on every game reboot

I like to use the Cortana skin from the Halo Mash-Up pack. However, every time I boot up the game my skin reverts back to the default Steve skin. This happens on both of my accounts, and it's only happened after the Village and Pillage update. It gets really tedious, having to go to the Marketplace, searching for Halo (I haven't actually bought the pack), selecting the Halo Mash-Up pack, going down to the skins section and equipping the Cortana skin every time I launch the game. Please fix this!