我自己找到了解决办法。它返回默认的帖子类型，而不是排除自定义的帖子类型，这很适合我的需要。

function my_breakfast_query ( $query ) {
// not an admin page and is the main query
if (!is_admin() && $query->is_main_query()){
if (is_tax( \'food\', \'breakfast\' )){
  $tax_query = array(
    \'relation\' => \'OR\',
     array(
        \'taxonomy\' => \'category\',
        \'field\' => \'id\',
        \'terms\' => array( 366 )
     ),
     array(
        \'taxonomy\' => \'food\',
        \'field\' => \'id\',
        \'terms\' => array( 364 )
     )
  );
  $query->set(\'post_type\',\'post\'); // Added this line to get a working solution
  $query->set(\'tax_query\', $tax_query);
 }
 return $query; // Added this line to get a working solution
 }
}
add_action( \'pre_get_posts\', \'my_breakfast_query\' );