Zoho CRM Calendar / Zoho Calendar Sync not adding events to which I am added

Zoho CRM Calendar / Zoho Calendar Sync not adding events to which I am added

Hello,

I have Zoho CRM Calendar synced with Zoho Calendar.

When I create an Event in my calendar and I add another User as a Participant, the Event appears in the other User's Zoho CRM Calendar. This is fine and works as expected. 

When the other User views their Zoho Calendar, the new Event has not synced (I wait extended periods of time to allow the sync to happen.)

Events created by the other User do sync across, so this problem seems particular to Events to which the User is invited not syncing up with Zoho Calendar.

Is this a known issue or do I have a setting incorrectly configured?