This has been an ongoing issue for pretty much a year but there hasn’t been any talk about fixing this fairly annoying bug with custom skins.

When navigating to the Classic Skins tab and selecting a custom skin from a skin pack, it will change to a Steve or an Alex after selecting Equip. It will only save as a Steve or an Alex if you apply a custom skin to an empty slot from the Dressing Room tab (where it says Create Character instead of Edit Character). If you do, however, choose a custom skin over a slot that already has a custom skin over it (when it says Edit Character), it will stay as the previous skin and won’t change at all.

This bug only occurs with some skins and I’m not sure why that is. It has been happening since before the UI change.