When I try to add an image or file to a field from the media library, I can't see my images. I can see how many files I've got -- it displays "Images (5)" at the top, as it should -- but it won't actually display anything below that. I noticed that a few people have posted about this problem with no real solution, so I thought I'd share how I fixed it myself.
I played with the frame's URL and noticed that it works just fine if I remove "&type=image" or "&type=file". Marvellous! :D
To get rid of this bit of the URL permanently, I edited js/input-actions.js to remove "&type=image" from lines 421 & 1486 and "&type=file" from line 365. It works perfectly now.