Azure Translation endpoint example code FAILS in VS Code Polyglot Notebook

Question

QUESTION: Why would the following code work fine in a VS Pro, C# console app but fail in a VS Code Polyglot Notebook C# cell?

I am prototyping C# code in VS Code and Polyglot notebooks to translate text. I have successfully used Polyglot Notebooks to prototype non-Async C# code in the past.

In a C# notebook cell I have placed Azure's translation endpoint example C# code (which works outside Polyglot Notebook in a console app). That code follows ...

using System;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;

class Program
{
    private static readonly string translationEndpoint = "https://api.cognitive.microsofttranslator.com";
    private static readonly string apiKey = "<API Key here>"; // Replace with your actual API key

    public static async Task Main()
    {
        string sourceText = "Hello, world!";
        string targetLanguage = "es-ES"; // Spanish

        string translationResult = await TranslateTextAsync("en-US", targetLanguage, sourceText);

        if (translationResult != null)
        {
            Console.WriteLine($"Source text: {sourceText}");
            Console.WriteLine($"Target language: {targetLanguage}");
            Console.WriteLine($"Translation: {translationResult}");
        }
        else
        {
            Console.WriteLine("Translation failed.");
        }
    }

    public static async Task<string> TranslateTextAsync(string sourceLang, string targetLang, string text)
    {
        using (HttpClient client = new HttpClient())
        {
            client.DefaultRequestHeaders.Add("Ocp-Apim-Subscription-Key", apiKey);

            string payload = $@"
                {{
                    ""text"": ""{text}"",
                    ""to"": ""{targetLang}""
                }}";

            StringContent content = new StringContent(payload, Encoding.UTF8, "application/json");
            HttpResponseMessage response = await client.PostAsync($"{translationEndpoint}/translate?api-version=3.0", content);

            if (response.IsSuccessStatusCode)
            {
                string responseContent = await response.Content.ReadAsStringAsync();
                string translation = responseContent.Substring(1, responseContent.Length - 3); // Extract translation from the JSON response
                return translation;
            }
            else
            {
                return null;
            }
        }
    }
}

... the only alteration I made was removing the args parameter from Program.Main( string[] args).

Calling Program.Main() results in the message...

==> Translation Failed

QUESTION: Why would this code work fine in a VS Pro, C# console app but fail in a VS Code Polyglot Notebook C# cell?