Getting wrong value in bar chart when using a transform index

Getting incorrect value when I'm creating a bar chart from an index that I have created using Elasticsearch Transform. Basically a group by table from the main table. Below is the bar chart image.

And below is the sample of the transformed group by table.

2

The sum for xyz should be 2192 for 1st June 2021 but in the bar chart, it is showing 2188. The time field for the index pattern is "report_date".

Why I'm getting the wrong value in the chart? Please help!!

Could you send the transform config you are using?
Since the difference between expected and actual numbers is small (2192 vs 2188) I'm suspecting some kind of data delay on the day boundaries.

Please find below the configuration.

{
  "id": "test_index",
  "version": "7.11.1",
  "create_time": 1622710097691,
  "source": {
    "index": [
      "xyz_generic"
    ],
    "query": {
      "bool": {
        "should": [
          {
            "match_phrase": {
              "operation.keyword": "operation_1"
            }
          }
        ],
        "minimum_should_match": 1
      }
    }
  },
  "dest": {
    "index": "test_index"
  },
  "frequency": "1m",
  "sync": {
    "time": {
      "field": "datetime",
      "delay": "60s"
    }
  },
  "pivot": {
    "group_by": {
      "report_date": {
        "date_histogram": {
          "field": "report_date",
          "calendar_interval": "1d"
        }
      },
      "partner1.keyword": {
        "terms": {
          "field": "partner1.keyword"
        }
      }
    },
    "aggregations": {
      "partner2.keyword.value_count": {
        "value_count": {
          "field": "partner2.keyword"
        }
      }
    }
  },
  "settings": {
    "max_page_search_size": 500
  }
}

I'm suspecting that somehow kibana visual could not fetch correct values from the index created by Transform. Because, if we see the transform sample (fig 2), it is showing the correct value but when by using that index, we are creating the bar chart, it is reflecting the incorrect value.