There seems to be a bug when using the drag-and-drop method to add a folder to the Documents and Media portlet. When I drag-and-drop and folder with JPG images, it appears like the attached snapshot (docs-media-bug-1.png). When I refresh the page, the folder disappears. There are no errors in the console.
I experienced a different behavior when adding a folder with TXT files. When I added the folder, it first appeared like the attached snapshot (docs-media-bug-2.png}. When I clicked on the folder, I was given the following error messages (docs-media-error-log.txt).