Default order doesn’t work correctly

Something is overriding the results. Trying to change the order to something else with orderby parameter in the URL doesn’t work.

Common causes include plugins that are related to sorting posts, for example Intuitive Custom Post Order. Themes may also affect this.

If you can’t figure out the source of the problem, one solution is to add Relevanssi-specific override to your theme functions.php:

add_filter( 'relevanssi_modify_wp_query', 'rlv_override_orderby' );
function rlv_override_orderby( $query ) {
    $query->set( 'orderby', array( 'relevance' => 'DESC' ) );
    return $query;
}

Thanks for your quick reply. I couldn’t figure out which plugin causes the issue, but solved the issue with the additional code.