This bug only began after Minecraft updated to the 1.14.1 Hotfix. It is affecting the skins that I have previously purchased by changing their usage to "limited". The skin pack that I am using is the Halo one, but I haven't checked to see if any others were affected. Prior to the 1.14.1 Hotfix, I could use all of my skins in multiplayer with absolutely no issues. This bug is very annoying in multiplayer, as I don't want to go back to the stone ages of Minecraft where only Steve could be used as a skin. Thanks.