Same 17 appointments always get added to Outlook

Same 17 appointments always get added to Outlook

I use to sync only Zoho categories with Outlook and now have changed it to all appointments/events and now whenever I synch I always get the same message 17 Additions to Outlook from Zoho but the appointments are already in outlook and they do not get added, as there is still only one instance of the 17 appointments i.e. no duplicates

Why is it still prompting me to add the 17 appointments and I save and accept then the sync completes.  There must be a bug here, please advise, thanks.