In method send_notification() at line 309

Freeform_notifications.php

		if ( ! empty($order_ids))
		{
			//this makes sure that any fields in 'fields' are in the
			//order set as well. Will add missing at the end like this
			$field_loop_ids = array_merge(
				$order_ids,
				array_diff($field_loop_ids, $order_ids)
			);
        } else {
            $layout = $this->composer_field_order( $form_data['form_id'] );
            $field_loop_ids = array_merge( $layout , array_diff( $field_loop_ids , $layout ) );
        }