This game needs more guitar skins.
I think your skin is just didn't downloaded properly. Sometimes it takes a while.
Rust SDK is outdated. Devs decided that is sucks and recommended to use in-game Workshop instead. Though it'll be nice if we could get FBX model of any item directly from workshop. If you really need any of these models - try to use any model ripper (Intel GPA Ripper, but it'...