Event properties not set flutter web

Hi,

I am developing a flutter web application.

I am tracking events using the flutter sdk version 3.14.0. The events are tracked and work.

The issue is with event properties: they are not tracked. The JSON sent does not contain them.

Here is how I track an event:

Amplitude.getInstance("instance_name").logEvent(
  "activity_create",
  {
    "activity_type": type.toString(),
  },
  null,
  null,
  false,
);

It looks a little bit different than the guide but that is because the code in the guide is outdated - using 

analytics.logEvent('MyApp startup', eventProperties: {
      'friend_num': 10,
      'is_heavy_user': true
    });

throws compile errors.

Any idea on what might be wrong?