Hi @nf_mastroianni,
Welcome to the community!
Thank you for the bug report. We also identified on our side a problem with the authentication, specifically to create a repository with the init.
We are currently fixing the bug: fix(init): Fix failed to create repository error in init by xrutayisire · Pull Request #1179 · prismicio/slice-machine · GitHub
It's the equivalent of what you're doing, logout to flush the stale authentication and login again.
It should be released next week 
Thank you,
Xavier