title: Elasticsearch bool query with filter terms and string search returning inconsistent results
body: <p>I'm running the following query against Elasticsearch that matches documents based on a string search and property terms match.  When I pass a single term, I get the expected results, but when I add a second term, I don't get the same results.  Ideas?</p>
  
  <pre><code>{
    "_source": {
      "includes": [
        "docID"
      ]
    },
    "query": {
      "bool": {
        "must": [
          {
            "terms": {
              "userID": [
                1,
                2,
                71
              ]
            }
          },
          {
            "query_string": {
              "query": "**test**",
              "fields": [
                "attachment.content"
              ]
            }
          }
        ]
      }
    }
  }
  </code></pre>
  
  <p>If I pass only userID 1, and omit the others, I get the docIDs I expect (i.e. 1,4,8), but when I pass all three userIDs I have several docIDs missing from the results (i.e. 1, 6, 8, but no 4).  Using Elasticsearch 6.5.</p>
  
  <p>Hopefully someone understands better than I why this is! </p>
  
  <p>Thanks in advance!</p>