This is usually the result of using the Smart Filter feature (the eye on the top). I've been meaning to look into the true cause.
Interesting, yeah it seems to work a little better when I turn off the filter but I have a lot of movies... once I start scrolling down further the bar itself disappears completely until I reach the end. It only displays for about the first 20 listings.

Edit: I take that back. If I close 360 and open it again with the filter already off, it works (filter off) but not when I enabled the filter again.