Allow Empty Search not working

I have this set up with multi-search and it worked just fine recently. Today I was told that the search form is allowing empty searches. If you visit the URL shown, and search with any selected category, it shows all records. If I leave the category empty, it works as it should. Doesn’t the “Allow Empty Search” setting require a value in the Search field, opposed to requiring only a Category be chosen?

The page I need help with: [log in to see the link]