I recently moved from elastic search 5.5 to 6.1.2. After moving to the new version, all elastic search wildcard queries on _id is not returning any hits. This  code used to work in 5.5. We verified this using my application as well as kibana. We have also taken care of having only one type mapping "doc" in a single index.

    POST group_topic/doc/_search
      "query":{"wildcard": {
                      "_id": "g*"

      "took": 0,
      "timed_out": false,
      "_shards": {
        "total": 5,
        "successful": 5,
        "skipped": 0,
        "failed": 0
      "hits": {
        "total": 0,
        "max_score": null,
        "hits": []

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