Also It ocours on Android Every time I open Minecraft On my Android Tablet my custom skin changes back to Steve or Alex and sometimes it change to a marketplace pack Skin that I Used Recently It started ocouring when updated to 1.12.0.28 I hope This Gets Fixed
Same problem here in Minecraft Android 1.12
Confirmed on Android
Until they fix This Bug Change your Skin to Steve or Alex and Then Change It To Your Own Skin Again When This Issue Happens