Problem uploading Rust skin from Unity to Steam Workshop

exception: tried to initialize steamworks twice in one session! steamworks.steam api.init () (at assets/plugins/steamworks/steamworks.net/steam.cs:54)

This is the error I keep getting when I hit create & upload.

My item id is set to 0 and the material is correct.

Has anyone encountered this and found a solution, or can shed any light towards a fix?

Thanks.