The sync and import feature is not working correctly. When I import using a calendar ID the plugin imports some events under the category url and some will import under the name of the calendar which it wasn't doing before.
Additionally, and more importantly, some events are not showing up that are showing on the Google Calendar.
About Google Calendar I will explain and check to see what are you missing, watch the video in this link : This Link.
1- The Google Calendar should be public to import
2- The timezone on WordPress and Google Calendar need match together
3- APIKey should be enabled for Google, check the client ID too
It has been explained how to do it in the video above
Cron Jobs, check these items :
1- Import manually for the first time so the API would be set in MEC.
2- Go to MEC Settings > Import/Export > Synchronization Tab , and copy the URL it provides.
3- Go to your site CPanel and use this URL in cron jobs
Please Note: Cron jobs is a feature of CPanel and you need to contact your host provider to set it.