I can't reproduce it regularly, but if I click around enough selecting different collections, I get an irritating bug where a collection comes up with only one resource showing (it's happened twice this morning, and 3 or 4 times yesterday). I eventually realized that all the other entries were scrolled off of the top (in a way that isn't possible to do using the scrollbar):

4.1 beta 3 is the first time I noticed it.