When code is run in an ArcGIS Online Notebook that produces an output file in Files pane and the code completes the Files pane does not refresh and it's not apparent that the output has been generated.
The Files pane has to be hidden and re-opened to display the output file.
The Files pane should refresh when the running of a cell completes.
As an alternative a refresh button could be added to indicate that the pane does not refresh itself, as is common in other ArcGIS applications...