Sending custom telemetry to azure insights

Question

I have a Java azure function (runtime 3.2.0) where I try to send some custom telemetry. I use the following code

TelemetryConfiguration config = TelemetryConfiguration.getActive()
TelemetryClient telemetry = new TelemetryClient(config);

telemetry.trackEvent("Test Event");
telemetry.trackTrace("Test Trace", SeverityLevel.Warning);

telemetry.flush(); // Not sure it is needed
When I check config.getInstrumentationKey() is is the correct key for the Application Insights I want to show the custom telemetry. However, I never receive the custom event and trace in my Insights. Also config.isTrackingDisabled() i false and config.getChannel() seems to make sense.

All code examples I have found and in the official documentation as well it seems to be all the code I need. When I use the logger from the ExecutionContext logs appears in Application inside, so my function has access to it. So I suspect I have overlooked some small important fact or there is some configuration of my function that is not set correctly.

Can anybody help me get custom telemetry to work on my java function?