Anyone come across this error when adding a Hosted Feature Service to ArcMap? We are testing out Portal for ArcGIS 10.5 but I am still at ArcMap 10.3.1 (unsure if this is the issue). I can successfully publish hosted feature services to Portal, view them in a web map, see them on the federated ArcGIS Server in 'Hosted' services folder but I cannot add them to ArcMap.
Error: Could not add the specified data object to the map.
Unable to return internet proxy for server types other than arcgis server,