I have a published geoprocessing service that allows uploads. I have a web mapping application where I've added the geoprocessing tool as a widget using the REST URL. The data type of the 'Input File' parameter is GPDataFile. After creating the widget, my 'Input File' field in the widget interface has no ability to open a file window and select a file. It only has a string entry box (first screenshot). Conversely, if I open the tool in the web map using the generic AGOL map viewer, I am given the choice of how I want to input the file: URL or Upload File (second screenshot). This works precisely as intended.
Frankly I'm at a loss as to why I can't get this working in the web mapping application. I can't imagine this is an error on ESRI's part, but on mine. Is there something I should be configuring in the web mapping application to allow for file dialogs to open?