A useful, common task for myself and those I supported in our user community, was adding point data via CSV file to a map. In the new map viewer, I only see an option to add from URL, where in classic viewer you can add from a file (on a computer). Do you expect users to load their data onto OneDrive or other cloud storage? If there is no option to add CSV from file going forward, you will leave a lot of people behind (when classic viewer is no longer available), especially those new to AGO and web mapping. Thanks for considering this comment.
Are you using Enterprise with the Map View Beta or ArcGIS Online?
Yes, I see that, as I described initially. Once I choose CSV, I can only add from URL and not from file/device, as I need to. Thanks.
I'm in the same boat. Did you every figure this out? Perhaps it is the license I have, through my organization?
A friend in GIS with education license said first add it to your content library in AGO. Double-check it won't add directly as I was trying as there have been software updates since then.