Drag and Drop Upload: Why it does not show in mobile devices?

Drag and Drop form looks great on the computer.

On the Phone, the Box appears for a milli-second then disappears and is replaced by another Upload File button.

This is because the scripts that make the widget work will not behave the same in a mobile device, do note that the script for this widget is very complex and the functionality will not be the same in a mobile device than it works in a computer, for example, in a mobile device you're not allowed to drag fields between the opened apps, so having the widget in the same way as the computer version will not make sense. 

However, the widget should work as upload field button, files should still be sent to your account and you should be able to view it in the submissions page.