elasticsear高亮问题

我的mapping如下

PUT hotel
{
  "mappings": {
    "properties": {
      "id": {
        "type": "keyword"
      },
      "name": {
        "type": "text",
        "copy_to": "all"
      },
      "address": {
        "type": "keyword",
        "index": false
      },
      "price": {
        "type": "integer"
      },
      "score": {
        "type": "integer"
      },
      "brand": {
        "type": "keyword",
        "copy_to": "all"
      },
      "city": {
        "type": "keyword"
      },
      "starName": {
        "type": "keyword"
      },
      "business": {
        "type": "keyword",
        "copy_to": "all"
      },
      "location": {
        "type": "geo_point"
      },
      "pic": {
        "type": "keyword",
        "index": false
      },
      "all": {
        "type": "text",
        "analyzer": "ik_max_word"
      }
    }
  }
}

插入一条文档

POST /hotel/_doc
{
  "id": 339952837,
  "name": "如家酒店(北京良乡西路店)",
  "address": "良乡西路7号",
  "price": 159,
  "score": 46,
  "brand": "如家",
  "city": "北京",
  "starName": "二钻",
  "business": "房山风景区",
  "location": "39.73167, 116.132482",
  "pic": "https://m.tuniucdn.com/fb3/s1/2n9c/3Dpgf5RTTzrxpeN5y3RLnRVtxMEA_w200_h200_c1_t0.jpg"
}

我的高亮查询如下

GET /hotel/_search
{
  "query": {
    "match": {
      "all": "如家"
    }
  },
  "highlight": {
    "fields": {
      "name": {
        "require_field_match": "false"
      },
      "brand": {
        "require_field_match": "false"
      }
    }
  }
}

得到这样的结果：

name、brand、business属性都copy_to到all属性中了，"require_field_match": "false"(也不必须匹配字段了)。

问题：brand能高亮，name不能高亮是什么原因？