my speech to text doesnt recognized multi channel

Question

when I upload my own file in the ingestionClient, it works but when I use the samplecode in Github it doesn't work and only give me a single channel. so it doesn't pick up the multi speakers.

it works here: https://speech.microsoft.com/portal/callcenter

but the one from the SampleCode is not working:
https://github.com/Azure-Samples/cognitive-services-speech-sdk/tree/master/scenarios/csharp/dotnetcore/call-center

if (inputAudioURL is string inputAudioURLValue)
{
	string transcriptionId = await CreateTranscription(inputAudioURLValue);
	await WaitForTranscription(transcriptionId);
	Console.WriteLine($"Transcription ID: {transcriptionId}");
	JsonElement transcriptionFiles = await GetTranscriptionFiles(transcriptionId);
	var transcriptionUri = GetTranscriptionUri(transcriptionFiles);
	Console.WriteLine($"Transcription URI: {transcriptionUri}");
	transcription = await GetTranscription(transcriptionUri);
}
else
{
	throw new ArgumentException($"Missing input audio URL.{Environment.NewLine}");
}

var phrases = transcription
	.GetProperty("recognizedPhrases").EnumerateArray()
	.OrderBy(phrase => phrase.GetProperty("offsetInTicks").GetDouble());
transcription = AddOrChangeValueInJsonElement<IEnumerable<JsonElement>>(transcription, "recognizedPhrases", phrases);
var transcriptionPhrases = GetTranscriptionPhrases(transcription);
SentimentAnalysisResult[] sentimentAnalysisResults = GetSentimentAnalysis(transcriptionPhrases);
JsonElement[] sentimentConfidenceScores = GetSentimentConfidenceScores(sentimentAnalysisResults);
var conversationItems = TranscriptionPhrasesToConversationItems(transcriptionPhrases);
var conversationAnalysisUrl = await RequestConversationAnalysis(conversationItems);
await WaitForConversationAnalysis(conversationAnalysisUrl);
JsonElement conversationAnalysis = await GetConversationAnalysis(conversationAnalysisUrl);

string simpleOutput = GetSimpleOutput(transcriptionPhrases, GetSentimentsForSimpleOutput(sentimentAnalysisResults), GetConversationAnalysisForSimpleOutput(conversationAnalysis));
string fullOutputFilePath = null;

if (outputFilePath is string outputFilePathValue)
{
	fullOutputFilePath = outputFilePathValue;
	PrintFullOutput(outputFilePathValue, transcription, sentimentConfidenceScores, transcriptionPhrases, conversationAnalysis);
}