I am able to reproduce the “no results” issue. It occurs when you start with the “view all categories” option. You then click on the next page of members at the top and go to page 2. Then when you click on another category on the left it always says “no results”. Then when you click on the category again it finds them. You can see it happen here:
Click the next set of members at the top, and then a catagory on the left and it happens.