Synonym search filter

Elastic Stack Elasticsearch
10

I tried to re-create your whole example now and all seems to work well for me, at least on 6.4.3.
See my the reproduction below to check where the differences might be? I haven't asked yet but which version of ES are you using?

DELETE /syn_search_test

PUT /syn_search_test
{
  "settings": {
    "index": {
      "analysis": {
        "filter": {
          "search_synonym_filter": {
            "type": "synonym",
            "lenient": true,
            "synonyms": [
              "well, in_force, serious, undecomposed, commodity"
            ]
          }
        },
        "analyzer": {
          "search_synonyms": {
            "type": "custom",
            "tokenizer": "keyword",
            "filter": [
              "lowercase",
              "search_synonym_filter"
            ]
          }
        }
      }
    }
  }
}

POST /syn_search_test/_doc/_bulk
{ "index" : { "_id" : "1" } }
{ "text":"This dog is the well one"}
{ "index" : { "_id" : "2" } }
{ "text":"This dog is the in_force one"}
{ "index" : { "_id" : "3" } }
{ "text":"This dog is the serious one" }
{ "index" : { "_id" : "4" } }
{ "text":"This dog is the undecomposed one" }
{ "index" : { "_id" : "5" } }
{ "text":"This dog is the commodity one" }
{ "index" : { "_id" : "6" } }
{ "text":"This dog is the honorable one" }
{ "index" : { "_id" : "7" } }
{ "text":"This dog is the skilful one" }
{ "index" : { "_id" : "8" } }
{ "text":"This dog is the dependable one" }
{ "index" : { "_id" : "9" } }
{ "text":"This dog is the expert one" }
{ "index" : { "_id" : "10" } }
{ "text":"This dog is the honest one" }


GET /syn_search_test/_search
{
  "query": {
    "match": {
      "text": {
        "query": "well",
        "analyzer": "search_synonyms"
      }
    }
  }
}

Gives:

{
  "took": 11,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": 5,
    "max_score": 1.2039728,
    "hits": [
      {
        "_index": "syn_search_test",
        "_type": "_doc",
        "_id": "5",
        "_score": 1.2039728,
        "_source": {
          "text": "This dog is the commodity one"
        }
      },
      {
        "_index": "syn_search_test",
        "_type": "_doc",
        "_id": "2",
        "_score": 0.9808292,
        "_source": {
          "text": "This dog is the in_force one"
        }
      },
      {
        "_index": "syn_search_test",
        "_type": "_doc",
        "_id": "4",
        "_score": 0.9808292,
        "_source": {
          "text": "This dog is the undecomposed one"
        }
      },
      {
        "_index": "syn_search_test",
        "_type": "_doc",
        "_id": "1",
        "_score": 0.6931472,
        "_source": {
          "text": "This dog is the well one"
        }
      },
      {
        "_index": "syn_search_test",
        "_type": "_doc",
        "_id": "3",
        "_score": 0.2876821,
        "_source": {
          "text": "This dog is the serious one"
        }
      }
    ]
  }
}