A few of our sales engineers are having issues syncing their Zoho calendars to Outlook 2010 calendars. The issue started recently. I verified their settings of the Outlook plug-in, and the "Added to Zoho" category is properly checked. When they click "Sync Calendar," the Events Synchronization pop-up window appears but the Add, Update, Delete quantities are zero. 

I've checked everything I can on my end. Does anybody have any suggestions?

Thank you!

John Galich