Adding a new photo (memory) using drag-and-drop works fine if there's already something in the Memories section, but if there's nothing it doesn't work.
Only tested with JPGs
Drag-and-drop does work when there are no memories yet, but the drop area is quite small, so it's understandable that you might think that it doesn't work at all. When you are in the process of dragging and preparing to drop the image, move your mouse fairly high on the screen -- the drop target will certainly appear if you move your mouse over the ADD MEMORIES button. It would be nice if the drop area were significantly larger.
So it does - thank you.