Each single filter item will return any (OR) matching items selected.
For example. If you searched for an Expert Located in ‘Egypt’ OR ‘Syria’ the search result would return any person meeting either criteria.
Each filter section will return items matching both (AND) filter sections.
For instance if you search for an expert located in ‘Egypt’ OR ‘Syria’ AND a geographical expertise of ‘Iran’ the search will only return a results for people located in either country who also have a geographic speciality of Iran and will exclude those without a speciality in Iran.
Try removing some filter items or resetting your search.