We use CRM Calendar to schedule health care appointments, which are often re-occurring. When an appointment is deleted or changed in CRM, the client's calendar is not updated. This leads to clients receiving appointment reminders for deleted and canceled appointments.

Also, CRM Calendar is not accurately sync'ing with google calendar or Zoho Calendar. Changed or deleted events in CRM Calendar, are not reflected as changed, canceled or deleted on google or zoho calendar. 

I have reached out to support several times regarding this, and have not received a response that fixes this sync'ing issue.