It already happened to me a couple of times, suddenly drag and drop just isn’t working anymore…? What the ****?
Rebooting solves the issue, but there is an easier way:
Open Windows Explorer, left click a file/folder and hold the left mouse button down. Then press the <ESC> -key and…. Tada! Drag and drop is working again!
This issue is caused by an application locking the option to drag and drop.