Desktop notifications aren't working
If desktop notifications were enabled on your messages, but you aren't getting notifications, you may need to check your operating system notification settings. Here's how:
Click on the notifications icon at the bottom right corner of your taskbar then click the expand button if your settings dashboard is not already expanded.
Make sure that Focus Assist is turned off. Focus Assist prevents notifications from being displayed.
Click the All settings icon in your settings dashboard. In the all settings menu, type "Notifications" in the search at the top of the page and select "Notifications & Actions settings".
In the Notifications and Actions settings screen, scroll down and find Google Chrome. Make sure that Chrome has notifications turned on.
Click the Notifications Center button at the top right of the screen and make sure Do Not Disturb is turned off.
Open System Preferences and select Notifications
Scroll down to Google Chrome. Make sure Chrome has either Banners or Alerts enabled.