Search buttons not working

I've added user filters to my reports but search buttons that appear when I click on those filter columns are not working. As soon as I move the cursor to the search box, the search icon gives way to a 'x' mark and when I type what I would like to look for, just nothing seems to happen.

This is the case both in the 'View' mode within Reports as well as embedded view on my site.

Please help.