Category Thumbnail Display – How to display ONLY the main Category

Ideally, place this in a plugin (so it’s not overwritten when you update the theme):

function wpse_106185_elist_categories( $args ) {
    return $args + array(
        'depth' => 1,
    );
}

add_filter( 'listing_categories_args', 'wpse_106185_elist_categories' );

Alternatively, a quick fix is to edit this line…

$elist_categories_args = array( 'hide_empty' => 0 );

To…

$elist_categories_args = array( 'hide_empty' => 0, 'depth => 1 );