Drag & Drop Upload: Widget does not upload files.

I cannot get my files to upload when I drag and drop in the box. The headers change in the upload box, but no file shows up.

Also, I receive a submittion notice in my JotForm box, but there is no file attached.

I have been testing this and I'm able to replicate the issue on your form; however, the widget works as expected on a different form, it's possible that there was an issue at the moment of adding the widget to your form. 

May you please kindly try deleting the widget, clearing your forms cache and adding it once again? 

It's possible that the user who submitted your form replicated the same issue, as the widget is not required the form allowed the submission without the file, if you want to make the field required you may click on the gear icon and turn on the required property while editing your form on the builder. 

Let us know how it goes.