推送事件未被触发

Question

I've downloaded this https://github.com/Minishlink/web-push-php-example. There is a send notification button in it which fetch a php file which pushes a notification using webpush https://github.com/web-push-libs/web-push-php.

It was working for a while and then just stopped working. After it stopped working I replaced with a working copy I had and still didn't show the notification.

The response from fetch to send_push_notification.php shows

[v] Message sent successfully for subscription https://fcm.googleapis.com/wp/f6ST-d7Ek3o:APA91bH3ZaT_QYo...

but I don't see the push notification. I have a console.log in push event handler in service-worker and I don't see the push notification

The js which calls the fetch to php file(send_push_notification.php)

sendPushButton.addEventListener('click', () =>
navigator.serviceWorker.ready
  .then(serviceWorkerRegistration => serviceWorkerRegistration.pushManager.getSubscription())
  .then(subscription => {

    const contentEncoding = (PushManager.supportedContentEncodings || ['aesgcm'])[0];
    const jsonSubscription = subscription.toJSON();
    fetch('send_push_notification.php', {
      method: 'POST',
      body: JSON.stringify(Object.assign(jsonSubscription, { contentEncoding })),
    });
  })

);

The service-worker file:

    self.addEventListener('push', function (event) {
  console.log("PUSHRECEived");

  const sendNotification = body => {
        return self.registration.showNotification(title, {
            body,
        });
    };

    if (event.data) {
        const message = event.data.text();
        event.waitUntil(sendNotification(message));
    }
});

Edit It works after I restart my PC. What could be the reason.