I use push notifications for very important things, but I've noticed that Windows doesn't always display the notification or play the notification sound when a notification comes in, which is hugely problematic. If I'm looking at the bottom right, a "1" will appear, but no noise and no popup.
This seems to happen when I'm playing a YouTube video (in the background, on a different windows virtual desktop).
I have "focus assist" disabled. If it's relevant, the notifications are coming from Chrome.