I have just completed upgrading ArcGIS Enterprise to version 10.6.1 (Server, Portal and ArcGIS Data Store). I tested the CSV drag & drop using a web map in Portal for ArcGIS, and it works perfectly. However, our staff only use Web Applications (i.e. not Web Maps) as these are much cleaner and look better, especially for staff who rarely see spatial data. But when I try to drag & drop a CSV file onto a Web App...nothing happens.
Is there something else I need to configure to get this to work? Everything else seems to work, except this.