Vector Tile (SearchMvt) issues - .NET client

Elastic Stack Elasticsearch
1

This is related to a previous topic I raised: Elastic.Clients.Elasticsearch .NET client - calling Vector tile search API

I am attempting to update to the latest version of Elastic.Clients.Elasticsearch (v8.13.8).

As the SearchMvt now appears to be supported I can call it with proper typing and not have to use the low level client.

Here is my code

            var result = await _elasticClientProvider.Client.SearchMvtAsync(
                index, "geometry", zoom, x, y, 
                request =>
                {
                    request.Query(boolQuery)
                        .Fields(fields)
                        .GridPrecision(0)
                        .TrackTotalHits(new TrackHits(false))
                    .RequestConfiguration(configuration => configuration
                        .ContentType("application/vnd.mapbox-vector-tile")
                        .Accept("application/vnd.elasticsearch+json"));
                }, ct);

            return result.ApiCallDetails.ResponseBodyInBytes;

Which returns an error with this message:

Unsuccessful (406) low level call on POST: /my-index/_mvt/geometry/2/0/1?pretty=true&error_trace=true
 Exception: Request failed to execute. Call: Status code 406 from: POST /my-index/_mvt/geometry/2/0/1?pretty=true&error_trace=true. ServerError: Type:  Reason: "Content-Type header [application/vnd.mapbox-vector-tile] is not supported"

Ok so I will reverse the settings, and use mapbox-vector-tile in the Accept header, like what happened in the previous topic:

         .RequestConfiguration(configuration => configuration
                        .Accept("application/vnd.mapbox-vector-tile")
                        .ContentType("application/vnd.elasticsearch+json"));

# Audit exception in step 1 BadResponse:
System.Text.Json.JsonException: '0x1A' is an invalid start of a value. Path: $ | LineNumber: 0 | BytePositionInLine: 0.
 ---> System.Text.Json.JsonReaderException: '0x1A' is an invalid start of a value. LineNumber: 0 | BytePositionInLine: 0.

Which makes sense, as the JSON serializer wouldn't be able to read the returned binary.

However I can't set the Content-Type to "application/vnd.mapbox-vector-tile".
It always says not supported 406, like my first error.

Adding SearchMvtAsync<BytesResponse> doesn't seem to do anything.

Assistance appreciated, thanks.