我有一个最初返回结果的弹性查询。当我再次尝试使用search_after进行分页查询时，我得到了错误：Cannot use [collapse] in conjunction with [search_after] unless the search is sorted on the same field. Multiple sort fields are not allowed。就我所知，我只使用了一个字段per_id进行排序和折叠。我的查询结构是否不正确，或者我需要执行其他操作才能运行此查询？

GET /_search
{
    "query": {
        "bool": {
            "must": [{
                "term": {
                    "pform": "iphone"
                }
            }]
        }
    },
    "collapse": {
        "field": "per_id"
    },
    "pit": {
        "id": "g-ABCDDEFG12345678ABCDDEFG12345678==",
        "keep_alive": "5m"
    },
    "sort": [ 
      {"per_id": "asc"}
    ],
    "search_after" : [
      "ABCDDEFG12345678",
      123456
    ]
}