I filter out one category in DejaToday.
When I go then in DejaToday and tap one of the categories from top-row, it shows me the available selection of categories I can tick/untick.

It does show the categories ticked I want to see, *except* the 'no category' one. It always shows that one UNticked when you first enter Today app and show the categorie select screen.

To test you need to tick 'no category', press OK, then go back-button to main screen and enter DejaToday again, tap category on top and it shows the select screen where 'no category' will be unticked again.

It would be nice if it could remember the 'no category' thing being ticket better