fieldpath update does not work for array attribute fields

schema test_field_path {

    document test_field_path {

        field docid type long {
            indexing: attribute | summary
        }

        field arr_int type array<int> {
            indexing: attribute | summary
        }

        field summary_int type array<int> {
            indexing: summary
        }

        field arr_str type array<string> {
            indexing: attribute | summary
        }

        field summary_str type array<string> {
            indexing: summary
        }

        field arr_map type map<string, int> {
            indexing: summary
            struct-field key   { indexing: attribute }
            struct-field value { indexing: attribute }
        }

        field summary_map type map<string, int> {
            indexing: summary
        }

    }
}

{
    "put": "id:default:test_field_path::1",
    "fields": {
        "docid": 1,
        "arr_int": [1, 2, 3],
        "summary_int": [1, 2, 3],
        "arr_str": ["a", "b", "c"],
        "summary_str": ["a", "b", "c"],
        "arr_map": {"a": 1, "b": 2, "c": 3},
        "summary_map": {"a": 1, "b": 2, "c": 3}
    }
}

{
  "pathId": "/document/v1/default/test_field_path/docid/1",
  "id": "id:default:test_field_path::1",
  "fields": {
    "summary_map": {
      "a": 1,
      "b": 2,
      "c": 3
    },
    "docid": 1,
    "summary_int": [
      1,
      2,
      3
    ],
    "summary_str": [
      "a",
      "b",
      "c"
    ],
    "arr_map": {
      "a": 1,
      "b": 2,
      "c": 3
    },
    "arr_str": [
      "a",
      "b",
      "c"
    ],
    "arr_int": [
      1,
      2,
      3
    ]
  }
}

{
    "update": "id:default:test_field_path::1",
    "fields": {
        "arr_int[0]": {
            "assign": 4
        },
        "summary_int[0]": {
            "assign": 4
        },
        "arr_str[0]": {
            "assign": "d"
        },
        "summary_str[0]": {
            "assign": "d"
        },
        "arr_map{a}": {
            "assign": 5
        },
        "summary_map{a}": {
            "assign": 5
        }
    }
}

{
  "pathId": "/document/v1/default/test_field_path/docid/1",
  "id": "id:default:test_field_path::1",
  "fields": {
    "summary_map": {
      "a": 5,
      "b": 2,
      "c": 3
    },
    "docid": 1,
    "summary_int": [
      4,
      2,
      3
    ],
    "summary_str": [
      "d",
      "b",
      "c"
    ],
    "arr_map": {
      "a": 5,
      "b": 2,
      "c": 3
    },
    "arr_str": [
      "a",
      "b",
      "c"
    ],
    "arr_int": [
      1,
      2,
      3
    ]
  }
}