The latest Beta (3.5.5 Beta Build 45770) has a bug in that makes it completely useless!
It is impossible to reset the filter text to the empty string in the filter edit control at the top. It keeps resetting itself to the phrase "Filter Torrents" which of course does not match anything and will not accept an empty string for no-filter.
If you try to tab out of the edit control or click out of it, so that it loses focus with no filter set, it will just put back the "Filter Torrents" phrase into the edit control, which as previously mentioned, will not match anything.
This make it impossible to turn filtering off.