Azure Static Web App function API refusing connection from web app

I have a Blazor WASM app deployed to an Azure Static Web app with a managed .NET 8 isolated Azure Function API. When calling the API directly from Postman using the auto-generated web app URL + the API route I receive the expected response and can see a log in Application Insights. However when I call the same endpoint from within the deployed WASM application I receive an net::ERR_CONNECTION_REFUSED response and a request isn’t recorded in Application Insights. I have confirmed that this is functioning as expected locally.

The successful postman request:

The Log in application insights:

My appsettings.json file that is packaged with the Blazor WASM app:

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*",
  "ApiBase": "http://localhost:7071"
}

The launchSettings.json of the Azure Function App API:

{
  "profiles": {
    "Project.Api": {
      "commandName": "Project",
      "commandLineArgs": "--port 7071",
      "launchBrowser": false
    }
  }
}

The Azure Function app is deployed to the Azure Static Web App and the SendContactEmailFunction function is registered in Azure:

The error I receive in the console from the deployed Blazor WASM app:

How the HttpClient is registered:

var apiBase = builder.Configuration["ApiBase"]
              ?? throw new ArgumentException("API base address not found in config.");

builder.Services.AddScoped(sp => new HttpClient { BaseAddress = new Uri(apiBase) });

The code that is calling the API function:

var response = await HttpClient.PostAsJsonAsync("/api/send-contact-email", sendEmailRequest);

The Azure function code:

public class SendContactEmailFunction(ILoggerFactory loggerFactory, ISender sender)
{
    private readonly ILogger logger = loggerFactory.CreateLogger<SendContactEmailFunction>();

    [Function(nameof(SendContactEmailFunction))]
    public async Task<HttpResponseData> Run(
        [HttpTrigger(AuthorizationLevel.Function, "post", Route = "send-contact-email")] HttpRequestData req,
        FunctionContext executionContext, CancellationToken cancellationToken)
    {
        logger.LogInformation($"{nameof(SendContactEmailFunction)} function received a request.");

        var requestBody = await new StreamReader(req.Body).ReadToEndAsync(cancellationToken);
        var request = JsonConvert.DeserializeObject<SendContactEmailRequest>(requestBody);

        HttpResponseData response;

        try
        {
            if (request == null)
            {
                throw new ApplicationException("Unable to deserialize response.");
            }

            var emailCommand = new SendContactEmailCommand(
                request.Name,
                request.FromEmail,
                request.Message,
                request.RecaptchaResponse);

            var sendEmailResult = await sender.Send(emailCommand, cancellationToken);

            if (sendEmailResult.IsFailure)
            {
                logger.LogError("Send email command failed. Error: {Error}", sendEmailResult.Error.Message);

                response = req.CreateResponse(HttpStatusCode.BadRequest);

                var error = new ErrorResponse
                {
                    Code = (int)HttpStatusCode.BadRequest,
                    Message = sendEmailResult.Error.Message
                };

                await response.WriteAsJsonAsync(error, cancellationToken);
            }
            else
            {
                response = req.CreateResponse(HttpStatusCode.OK);

                await response.WriteAsJsonAsync("", cancellationToken: cancellationToken);
            }
        }
        catch (Exception e)
        {
            logger.LogError(e, "Exception occured. Error: '{Message}'", e.Message);

            response = req.CreateResponse(HttpStatusCode.InternalServerError);
            
            await response.WriteAsJsonAsync(ErrorResponse.Generic, cancellationToken);
        }

        return response;
    }
}