I'm adding a lot of skins and was doing some quick testing. Rock and hammer work fine. But when I put the bandana in the skin box no skins show up. But I can use /skin add bandana #### and it is accepted and added to the config just fine. Can somebody else confirm if the bandana works for them?
I'm thinking there might be a problem with the short name?

I believe you are using a wrong shortname. I'll send you a correct one in a few seconds

Merged post

There you go:mask.bandana
You can find it using Items Info or on my GitHub repository: https://github.com/IvMisticos/Rust/blob/master/Game%20Info/Items.md