I think I've tracked the issue with syncing between Zoho Calendar and Google Calendar. It seems to be related to monthly repeating events. If I create an event with any monthly repeating option either in Zoho or Google, the event won't sync to the other platform. If I create an event with that doesn't repeat or repeats weekly it seems to do fine.
In continuation with our previous post on all the exciting updates and improvements that have shaped Zoho Calendar over the past 12 months, Lets delve into more: Bring your calendars together- Introducing Zoho Calendar and Outlook calendar synchronisation