AWS Pinpoint events delayed and don't trigger journeys

Question

I want to create user journey's using AWS Pinpoint. My mobile app is made with Flutter and using Amplify package to create events)

pubspec.yaml

amplify_flutter: ^0.2.4
amplify_analytics_pinpoint: ^0.2.4

I am calling this method to add the event

Future<void> logLogin(String userId) async {
    await addEvent('_app.login', {PinPointAnalyticsKeys.userIdProperty: userId});
}

Future<void> addEvent(String eventName, Map<String, String> properties) async {
    AnalyticsEvent event = AnalyticsEvent(eventName);

    properties.forEach((key, value) {
        event.properties.addStringProperty(key, value);
    });

    Amplify.Analytics.recordEvent(event: event);
    await Amplify.Analytics.flushEvents();
}

Method handling the login:

Future<bool> performLogin(String username, String password) async {
    
    //Code that handle login using email/password => userId
    
    await _pinPoint.logLogin(userId);
}

My test journey: a user from a specific segment who does login should get an email right away.

I am having 2 issues:

Events get added to Pinpoint but after a delay (between 10 and 20min approximatively). Shouldn't it get added right away?

When event gets added (after the delay) no journey does get triggered, so no email sent, and the Pinpoint Journey Metrics doesn't change. What could be the reason?

Thank you all for your assistance, if I missed some details please let me know.