I followed Google's codelab "Adding Push Notifications to a Web App" (https://developers.google.com/web/fundamentals/codelabs/push-notifications/) - it works with Chrome.
But in Firefox 55 no notification shows up when I press the "Test Push Notification" button in about:debugging#workers, though in the console "[Service Worker] Push Received." is outputted.
No idea where to investigate first... Anyone can help?