Cannot access skin packs

throwaway account because i want an answer to this

I play on Windows 10, and all the skins packs I own don't show up in my menu. This isn't much of a bother to me since I mainly just use custom skins anyways, but it's been getting increasingly annoying for a while.

I think the straw that broke the camels back was when I got the Founders Cape, it won't show up in my menu, and the only way I can equip it is from the marketplace. It is really annoying to not be able to switch skins from the skin menu. Of course, I have my custom skins, but there's also skins from skin packs that I like to wear. I own a ton of skins (even special ones like the earth and dragon slayer skin, and of course the founders cape), and I find it really annoying to not have acess to those skins.

Is there a way to fix this? Much appreciated!