Custom Skins Resetting to Default Skins

I have been experiencing this issue for about a month. Every time I set a custom skin, I can only have it on until I close the game. It always resets to default when I open the game back up. At first it said my skin wasn't compatible with multi-player, but now it just goes back to default. I don't mind it much, but it gets annoying having to keep resetting my skin.