Before people provide me with a google search link YES I have searched for a solution previously. I've installed (and reinstalled) GOG Galaxy on my Mac (latest version of OSx). I run Galaxy and it stays open for about 10 seconds before getting the infamous Communication error. Looking at the log files I get this error message:

"Stop serving due to lack of user authorization info"

Any ideas on what might be causing this? I'm assuming Firewall but I've set it up so it will allow Galaxy to communicate.