为什么 whereHas 多对多关系查询有时失效？

关联关系：

public function territory()
{
      return $this->belongsToMany(
      Territory::class,
      'territory_hospital_relations',
      'hospital_id',
      'territory_id'
      )->withTimeStamps();
}.

查询：
a.

if(!empty($titles)){$model->whereIn('title', $titles);}

b.

if(!empty($territoryIds)){
$model->whereHas('territory', function ( $query) use ($territoryIds) {
   $query->whereIn('territory.id', $territoryIds);
  });
  }

ps:a,b同时执行的时候，筛选有时有效（下1），有时失效（下2）

打印的SQL查询：
1.

SELECT
    count( * ) AS AGGREGATE 
FROM
    `hospitals` 
WHERE
    `title` IN ( 北京电力医院 ) 
    AND EXISTS (
    SELECT
        * 
    FROM
        `territory`
        INNER JOIN `territory_hospital_relations` 
        ON `territory`.`id` = `territory_hospital_relations`.`territory_id` 
    WHERE
        `hospitals`.`id` = `territory_hospital_relations`.`hospital_id` 
        AND `territory`.`id` IN ( 134 ) 
        AND `territory`.`deleted_at` IS NULL 
    ) 
    AND `hospitals`.`deleted_at` IS NULL #有结果

2.

SELECT
    count( * ) AS AGGREGATE 
FROM
    `hospitals` 
WHERE
    `title` IN ( 北京电力医院 ) 
    AND EXISTS (
    SELECT
        * 
    FROM
        `territory`
        INNER JOIN `territory_hospital_relations` 
        ON `territory`.`id` = `territory_hospital_relations`.`territory_id` 
    WHERE
        `hospitals`.`id` = `territory_hospital_relations`.`hospital_id` 
        AND `territory`.`id` IN ( 84 ) 
        AND `territory`.`deleted_at` IS NULL 
    ) 
    AND `hospitals`.`deleted_at` IS NULL #没结果，如果不加title in （北京电力医院）的限制，结果集中存在territory的ID是84的数据

3.

SELECT
    `territory`.*,
    `territory_hospital_relations`.`hospital_id` AS `pivot_hospital_id`,
    `territory_hospital_relations`.`territory_id` AS `pivot_territory_id`,
    `territory_hospital_relations`.`created_at` AS `pivot_created_at`,
    `territory_hospital_relations`.`updated_at` AS `pivot_updated_at` 
FROM
    `territory`
    INNER JOIN `territory_hospital_relations` 
    ON `territory`.`id` = `territory_hospital_relations`.`territory_id` 
WHERE
    `territory_hospital_relations`.`hospital_id` IN ( 3292 )  #北京电力医院的id是3292
    AND `territory`.`deleted_at` IS NULL #这条sql的结果territory的值只有84，134