In case anyone else runs in to this, here is how to fix it. In php/admin-functions.php, add the following at the end of the foreach loop in fluff_do_bulk_update:
//add at the end of foreach($updates as $post_id => $update)
// update the term count in term_taxonomy table
$term = get_term_by( 'slug', $bulk['term'], 'gallery' );
$term_tax_id = array();
$term_tax_id[] = $term->term_taxonomy_id;
$output = wp_update_term_count_now( $term_tax_id, 'gallery' );