Bug? "Failed to create query" error against Elasticsearch 7.3

Grafana Cloud
1

Hi, I’m using Grafana Cloud (currently running 6.3.4, commit a557646), and am having difficulty writing queries against our Elasticsearch 7.3 deployment on Elastic cloud. The data source is configured correctly: the “Save and test” button gives me a green tick. However, when I try to query the data source from a Grafana widget, including in the Explore view, I receive an error saying “Failed to create query”. This seems to be the case for any query I write against the data source in Grafana: all the Elastic-backed widgets are blank right now. An example failed query from the error report is:

{
  "bool": {
    "filter": [
      {
        "range": {
          "@timestamp": {
            "from": "1569239907225",
            "to": "1569326307225",
            "include_lower": true,
            "include_upper": true,
            "format": "epoch_millis",
            "boost": 1.0
          }
        }
      },
      {
        "query_string": {
          "query": "fields.Event.Id:19002",
          "fields": [],
          "type": "best_fields",
          "default_operator": "or",
          "max_determinized_states": 10000,
          "enable_position_increments": true,
          "fuzziness": "AUTO",
          "fuzzy_prefix_length": 0,
          "fuzzy_max_expansions": 50,
          "phrase_slop": 0,
          "analyze_wildcard": true,
          "escape": false,
          "auto_generate_synonyms_phrase_query": true,
          "fuzzy_transpositions": true,
          "boost": 1.0
        }
      }
    ],
    "adjust_pure_negative": true,
    "boost": 1.0
  }
}

I think this is a bug, but want to rule out misconfiguration or similar first. Any ideas?