I have been experiencing a very strange bug within the game, and as much as I am currently using mods, the bug also occurred when playing the game without any mods. Apparently my pickaxe skin called "Hunter's Pickaxe" is "set" as my default skin, because no matter how much I select the skin when I create a pickaxe, it keeps the skin icon (in the inventory) but doesn't show it when equipped. The curious thing is that this really only happens with the pickaxe skins, because with any other item from the "Belonging" category it works fine, with or without mods.
Sorry if I have commited a mistake while typing, English is not my main language but i understand it.
I believe the way to reproduce it would be someone trying to craft the pickaxe with any skin.