Unable to use Portal web maps and data in VertiGIS Studio Designer

Our organization is testing the feasibility of transitioning our Geocortex Essentials maps to VertiGIS Studio Web.  We are starting with a test map, in our development environment, and have installed VertiGIS Studio Web on one of our development Essentials servers.  VSW was authenticated to our development test Esri Portal when installed.  VSW works, and has its installation app and one test web map created from a template available in the Portal.

We tried the suggestion of exporting an Esri Web Map configuration from one of our existing Geocortex Essentials maps.  To do this, we needed to create a new instance of Essentials that was authenticated to ArcGIS Portal, and then copy the needed site files from the existing instance of Essentials to the new instance.  This worked, and we exported the Essentials map as an Esri Web Map to our Dev Test Portal.  The map now exists on the Portal, but points to data from ArcGIS Server, which is not federated to Portal.  So whenever the map is opened, it prompts for the user to sign in to every layer.

In Portal, we added a URL Item for every ArcGIS Service that is needed for our Essentials based map.  The URL used is REST endpoint of the service.  The authentication is a username and password specific for the Portal.  These URL Items are now available on our portal and are shared to our organization.

The VertiGIS Studio Designer does not see the AGS Service URL Items, when we try to add them to a template map, they generate errors. 

We found similar errors when we tried adding a map component to the Blank Layout template, and pointing the map component to the web map exported from Essentials.

These errors all imply that CORS has not been configured correctly on our Portal server.  Or does it also need to be configured on the VertiGIS Studio Web server?  

I am not sure what needs to be set here to make the requests work.  Any suggestions about what additional settings are needed to make this work would be appreciated.