Outlook 2016 Plugin Error

Outlook 2016 Plugin Error

We have had a number of staff report the following error that comes up when clicking around Outlook 2016:

ex:System.NullReferenceException: Object reference not set to an instance of an object, 
at ZohoCRM_Plugin_for_Microsoft_Outlook.OLHandler.getRecipientsEmailAddress(Recipient olRecipient) 
at ZohoCRM_Plugin_for_Microsoft_Outlook.SalesBoxClass.ActiveExplorer_SelectionChange()

One user reported that it happened when she was copying text from one Email to another.

Any ideas what might be causing this?