This is a hard question to word correctly, but I'll do my best. When I originally purchased LR4, I used to be able to hold my cursor over a file in the preview row, and in addition to the filename, shutter speed, and ISO value in the pop-up box, more helpful info such as the date taken, file size, and pixel dimensions (6000x4000, or whatever resolution it is temporarily cropped to) was shown.
Now, three hyphens inside parentheses are the only thing that shows beside the basic information. I've tried restarting the application, restarting the computer, and searching the internet (a lot), but I can't figure out why this information is no longer available.
Here's a picture of what I see on each picture: