How do u search for a community topic

How do I search for a topic from this page:

https://premium.wpmudev.org/forums/

It has the search box (which says "Search for a community topic" but searching does not appear to be working e.g. search for the word "Beta" which is in the featured topics - cant find it, search for "membership" or "plugin" or "facebook" but also produces no results. I can clearly see these words in the discussion headings on the page.

I have tried with both Firefox and IE - in case it was some weird problem.

What am I doing wrong?? How do I find topics for a certain plugin?