Thanks for the detailed feedback,
In the current version, this is expected behavior because the search bar is a separate form that has a higher priority than the sidebar filters form. For example, if you re-type keywords and hit Search again, it resets the search filters, so the search bar works as the initial search form. To change this behavior, you can add the Category field to the search bar in HivePress/Settings/Listings/Search/Default Fields, then it’s possible to enter keywords and select the category in the same search bar.
Hope this helps