Skins from files change to 3 pixel arms instead of 4 each time the game is loaded, even if they were 4 pixels before

What it says in the summary. When using a skin from a file (not a skinpack skin or a character creator skin), I always select the 4 pixel arms. However, whenever I reopen the game, the arms are always set to 3 pixels and I have to reload the skin file to fix it. This does not just happen on my devices; it is also happening to other people I know.