You don't appear to have a service worker registered.

What do you mean? I took the code straight from the example, and it prints "worker registered" in the console when I add a logging call there.

I was looking at the site, and I don't see it. Digging a little deeper, you need to work more on SW. Right now it is hosted on https://www.tithess.gr/static/js/service-worker.ba9881a3a5f4... - this means the service worker is only working for the directory 'https://www.tithess.gr/static/js/', if you want the banner to appear you need to have the service worker directly in the root of the site (note, this is how service worker is intended to work).

Thanks, I looked everywhere for something defining the scope and couldn't find any solid documentation. The registration is in the head, I'll move it to the top level, though, thanks.