I found the problem, and a fix 🙂
If you open the /js/wpsl-gmap.js file and look for this code on line 625.
ajaxData.max_results = parseInt( $( "#wpsl-results .wpsl-selected-dropdown" ).text() );
ajaxData.radius = parseInt( $( "#wpsl-radius .wpsl-selected-dropdown" ).text() );
Replace it with this.
ajaxData.max_results = parseInt( $( "#wpsl-results .wpsl-selected-item" ).text() );
ajaxData.radius = parseInt( $( "#wpsl-radius .wpsl-selected-item" ).text() );
Can you let me know if this also fixes it for you?
Categories filters will be available in the premium version, but I don’t have a date when that will be ready. First have to finish writing the documentation for the 2.0 update, and create a site for the plugin itself. Once that is ready I will continue working on the premium version.