Possible bug with sorting dynamically mapped fields

[Evgeni_Dzhelyov]

We ingest a lot of custom logs in Elasticsearch. For the application logs we use a custom schema with dynamic mappings, but when sorting for some of the fields we hit a strange bug:

1. Sort by a dext.duration#double field which is mapped to double by a dynamic mapping:

    {
      "double": {
        "path_match": "dext.*#double",
        "mapping": {
          "type": "double"
        }
      }
    },

• And we get a Can't sort on field [__anonymous_]; the field has incompatible sort types: [DOUBLE] and [LONG] across shards!. It reports as __anonymous_.

• If I add a filter for dext.duration#double exists, see the screenshot, it returns results:

• I don't have documents where the field doesn't exist, so it's very strange behavior.

Can you advise what is the possible cause?
I can provide more debug information if needed, if you can guide me on how to debug it.