title: Continuous Kibana Transform is not updated as source index and has one checkpoint since creation
body: <p>Kibana 7.7.1</p>
  <p>I am creating a transform to do an aggregation on a true/false field per user's set of data.</p>
  <p>on the source index document can be updated with updated status (true/false) and also new data are coming. Source index frequency of change can be more than 1 hour.
  I am creating Transform sync on <code>@timestamp</code>
  I created as many transforms as i can with all frequency and sync/delay possibilities and it never updated after creation and has only one checkpoint of creation.</p>
  <p>I am not sure what am I doing wrong
  here is the transform API I used</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>PUT _transform/mytransform
  {
    "source": {
      "index": [
        "mysource"
      ],
      "query": {
        "bool": {
          "must": [
            {
              "match_all": {}
            }
          ],
          "filter": [
            {
              "match_phrase": {
                "myflag": false
              }
            },
            {
              "range": {
                "mydate": {
                  "lt": "now"
                }
              }
            }
          ],
          "should": [],
          "must_not": []
        }
      }
    },
    "dest": {
      "index": "mydest"
    },
    "frequency": "1h",
    "sync": {
      "time": {
        "field": "@timestamp",
        "delay": "24h"
      }
    },
    "pivot": {
      "group_by": {
        "userID.keyword": {
          "terms": {
            "field": "userID.keyword"
          }
        }
      },
      "aggregations": {
        "userDocID.keyword.value_count": {
          "value_count": {
            "field": "userDocID.keyword"
          }
        }
      }
    }
    }</code></pre>
  </div>
  </div>
  </p>