I created a web map in ArcGIS Online about a month ago. It is shared and visible to the public. I logged in and wanted to add another layer to the web map and I get "Download of Map Failed" error box, after I select my web map to load for editing. Has anyone else had this problem? After this message, you cannot do anything, other than exit from ArcGIS Online. FYI, I am using the latest version of FireFox.
Here is the URL of my web map if you would like to see it (without the new layer I am trying to add).
Thanks in advance for your help.