>The checkbox is there and I see number 145, but clicking on it does nothing, e.g. it only brings messages from the categories I have unfiltered.

The default is the filtering. So, the checkbox serves to bypass the filtering. So, if you have 145 messages, checking that checkbox could increase the count to something higher, if applicable. It is still not clear however when I read your message if it works or not. You mentioned "it does nothing", but you also mentioned "it only brings the messages".