(Using Beta 5)
I created a 'January' filter (and a 'February' filter), and after looking through some things I clicked 'clear'. Before the stats from all dates reloaded/reappeared I clicked on the filters again, and looked at 'February'. Nothing happened. No stats appeared.
This works fine if I wait for the stats to appear after pressing 'clear', and then applying the next date filter.
I've tried a similar thing by first clearing everything, and then filtering for hands I VPIP and closing the filter window. When they load, I click on the filters again and whatever I try to filter for further causes the same problem. I add another condition and nothing happens - no hands are displayed, and the players list just says 'loading'.
It works fine if I put in both conditions simultaneously and click apply.