I am trying to add map services to the map viewer from our server REST endpoint within an ArcGIS Online organization. I have previously been able to do this and save web maps with the organization using these services without a problem. However, today, when attempting to open a web map containing those services or adding them to a new web map, I am getting an error stating "the layer ___, cannot be added to the map." The REST is fine. I can open them in the JS or AGOL viewers from the REST endpoint. I can also add the map services and feature layers to a web map from my AGOL personal account and OTHER organization accounts. I checked my account settings and do NOT have the box next to "Allow access to the organization through HTTPS only" checked. I did try checking, saving, unchecking, saving and clearing browser caches over and over.
Any ideas? Many thanks!