Hi Nikola, there is two options in the Connect beta that are not working properly as I could see in my installation:

1. I have assigned an interval of 5 minutes to execute the cron job, but this cron job is generated to be executed every 15 minutes (the default option). https://imgur.com/eZb8Czu I have checked with WP-CONTROL, and I have changed this event to be executed every 5 minutes, but I think you need to check this for the rest of users who do not know what is WP-CONTROL. BTW, I'm doing the cron jobs inside Wordpress, because I have no option in my hosting server to create cron jobs, I mean I have no cPanel or Plesk to do that. 
2. https://imgur.com/CzgATKA As you can see in the image, I have selected one of the services I offer to be the default service that must be applied when I create an appointment in Google Calendar. Said this, when I create an appointment in Google Calendar it is not created for that service, but for the one I created first, more expensive, and that I think should be the first one in the database. So, the option is not working, as GC creates the even in the that other service. The only one to avoid this is to just connect the service I want in the advanced tab, but that makes obviously to lose the sync for the other services with Google Calendar, so this is not a solution.

  Could you check this and let me know if it's me of those options are not really working. Thanks, José Luis.