I can't login to the app either. No problem logging into the website (obviously, or I wouldn't be able to post this). When trying to login to the app, I get this error message: Post https://api.itch.io/login: x509: certificate signed by unknown authority.
This has been happening for at least a month. The only updates I've installed in that time is Java.
Mac OS El Capitan, 2.5 GHz Intel Core i5, 16 GB RAM