Symptoms

Item Reference Event
 

Diagnoses

When we attempt to add the Item Reference Event to the canvas in K2 Designer for Visual Studio or K2 Studio, the wizard challenges for credentials when we enter the URL to the SharePoint site. Regardless of what credentials are used (email address for AAD or our on-premises domainusername account) the wizard challenges for credentials on a loop.
 

Resolution 

Item Reference Event that was being used is essentially a SharePoint 2010 event and will not integrate in to SharePoint Online/SharePoint 2013. Advised when building flows and application, customer and respective development team would have to have to utilize the SharePoint 2013 wizards to properly link to SharePoint Online/2013.