I play the native Linux version from Steam, I also own all DLC, including the skins. However, one skin, the Aloha skin, does not appear in game. I have double checked that I do in fact own it. The skin DLC also does not appear when I right click the game in my Steam library and view DLC. I suspect you may simply have forgotten to enable this particular skin DLC for the Linux platform.
Customer support service by UserEcho