Message's listen not working on new created subscription in flutter web environment

[sohyuyuan]

Pubnub Dart SDK version: ^4.0.0-beta.0
Dart SDK version: 2.14.3
Fltuter version: Flutter 2.5.2

Works fine in mobile applications.
Mobile application output:

I/flutter (26388): Message no. 1
I/flutter (26388): Message no. 2
I/flutter (26388): Message no. 3
I/flutter (26388): Message no. 4
I/flutter (26388): Message no. 5
I/flutter (26388): Message no. 10
I/flutter (26388): Message no. 11
I/flutter (26388): Message no. 12
I/flutter (26388): Message no. 13
I/flutter (26388): Message no. 14
I/flutter (26388): Message no. 15

The issue occurs at flutter web.
Flutter web console output :

I/flutter (26388): Message no. 1
I/flutter (26388): Message no. 2
I/flutter (26388): Message no. 3
I/flutter (26388): Message no. 4
I/flutter (26388): Message no. 5

Code:

Future<void> testPubNub() async {
    var pubnub = PubNub(
        defaultKeyset: Keyset(
            subscribeKey: 'subKey',
            publishKey: 'pubKey',
            uuid: UUID('uniqueId')));

    // Subscribe to a channel
    var channel = "getting_started";

    var subscription = pubnub.subscribe(channels: {channel});
    subscription.messages.listen((message) {
      print(message.content);
    });

    // Send a message every second for 5 seconds
    for (var i = 1; i <= 5; i++) {
      await pubnub.publish(channel, 'Message no. $i');
      await Future.delayed(const Duration(seconds: 1));
    }

    // Unsubscribe and quit
    await subscription.cancel();

    var channel2 = "getting_started2";

    var subscription2 = pubnub.subscribe(channels: {channel2});
    subscription2.messages.listen((message) {
      print(message.content);
    });

    // Send a message every second for 5 seconds
    for (var i = 10; i <= 15; i++) {
      await pubnub.publish(channel2, 'Message no. $i');
      await Future.delayed(const Duration(seconds: 1));
    }

    // Unsubscribe and quit
    await subscription2.cancel();
  }

Update:
The above issue is happening in local debugging.
After building the webpack and using http-server to serve it at local, it's working fine.

[are]

Hello! Thanks for reporting your issue!

Could you please enable logging as described here and send the logs to our PubNub Support? This way we can troubleshoot this faster and avoid leaking your private information. Thanks!