Vega chart in Kibana 7.9 doesn't change with different date ranges

I used Vega-lite command to create a time series chart. However, the chart doesn't change no matter which date range I select. It always show the whole set of data. I set "%timefield%": "timestamp", which is the name of my date field. I am new to Vega-lite and not sure how to debug it. In my Kibana, it says this visualization doesn't support inspect. I read some discussion about this but couldn't figure out what is the issue here. Really appreciate some help here. The following is my Vega code:

    { "$schema": "https://vega.github.io/schema/vega-lite/v2.json",
      "title": "Volume",
      "width": 800,
      "height": 300,
      "data": {
        "name": "data1",
        "url": {
          "%context%": true,
          "%timefield%": "timestamp",
          "index": "testindex",
          "body": {
            "size": 10000,
            "_source": ["Volume","timestamp"]
          }
        },
        "format": {"property": "hits.hits"}
      },
      "transform":[
        {
        "calculate": "toDate(datum._source['timestamp'])",
        "as":"time"
        }
      ],
      "mark": {"type": "circle", "opacity": 0.3, "size": 100},
      "encoding": {
        "x": {
          "field": "time",
          "type": "temporal"
        },
        "y": {
          "field": "_source.Volume",
          "type": "quantitative",
          "scale": {"domain": [0, 400]}
        }
      }
    }

Your Elasticsearch query will get updated by the time filter, but maybe you haven't written a query that actually gives you the data you want. All that the %timefield% does is apply a time range filter to reduce the number of matches. Have you tried running this query in the Dev Tools with different time ranges?