resultCode is 0 for all requests in Application Insights - azure-application-insights

Question

I have a function app connected with an application insights instance.
When I look at the requests on application insights, all entries have a resultCode of 0, regardless of whether it was successful or not. How can I have the resultCode showing properly?
If I get it correctly, my function app is running at the version "3.0.14916.0".
Here is my startup:
public class Startup : FunctionsStartup
{
public override void Configure(IFunctionsHostBuilder builder)
{
builder.Services.AddLogging(loggingBuilder =>
{
var key = Environment.GetEnvironmentVariable("APPINSIGHTS_INSTRUMENTATIONKEY");
loggingBuilder.AddApplicationInsights(key);
});
builder.Services.AddSingleton(sp =>
{
var key = Environment.GetEnvironmentVariable("APPINSIGHTS_INSTRUMENTATIONKEY");
return new TelemetryConfiguration(key);
});
(...)
}
}
Edit 1:
In the comments it was asked why I am adding logging in Startup. I do it because, as far as I could verify, ILogger < MyClass > only logs to AI if I add logging in Startup.
Following is an example of an injected class. Note that this class is also used in other projects.
public class CosmosDbService : ICosmosDbService
{
private readonly IDocumentClient _documentClient;
private readonly ILogger _logger;
public CosmosDbService(IDocumentClient documentClient, ILogger<CosmosDbService> logger)
{
_logger = logger;
_documentClient = documentClient;
}
public async Task<UserData> GetUserAsync()
{
try
{
// Getting user here
// (...)
}
catch (Exception ex)
{
_logger.LogError(ex, "Error fetching user.");
throw;
}
}
}
This class is injected as:
builder.Services.AddSingleton<IDocumentClient>(sp =>
{
// This does not really matter for this question
var configuration = sp.GetService<IConfiguration>();
var connectionString = configuration.GetValue<string>("COSMOS_DB_CONNECTION");
var cosmosDbConnectionString = new CosmosDbConnectionString(connectionString);
return new DocumentClient(cosmosDbConnectionString.ServiceEndpoint, cosmosDbConnectionString.AuthKey);
});
builder.Services.AddSingleton<ICosmosDbService, CosmosDbService>();

Answer 1

This answer from #PeterBons helped me fixing the wrong resultCode as well.
Basically I was importing the wrong package: Microsoft.Extensions.Logging.ApplicationInsights
I changed it to Microsoft.Azure.WebJobs.Logging.ApplicationInsights and removed the code in Startup. Now I got the resultCode properly filled in again.