I just installed 2.8.6p1 on an iMac running OS X 10.8.4. When I bring up the open file dialog and choose to sort by filename (ascending or descending) the files are listed in what appears to be two or three groups. Each group is sorted but obviously the entire list should be sorted properly. I have a list with hundreds of images files so this really makes it very difficult to find a file in the list.
I know there is an older (fixed and closed) issue covering this on Snow Leopard but the problem is back on Mountain Lion.