I just installed Portal 10.4.1 and expected to see the 'move to basemap' option. Does anyone know when this will be available in portal?
More info: In ArcGIS online, you can create a composite basemap by adding an additional tiled map service, and then choosing the 'move to basemap' option as in the screen shot. I don't see this option in the context menu for a tiled map service in Portal.