No Notifications

Why this happens?

You are not getting any message notifications and this is usually because the notification settings was disabled.

Go to Windows and search for Settings
Go to System and then Notifications and make sure it is enabled by clicking the toggle 'On'
Go to Teams, click the ellipsis () next to your avatar at the upper right-hand side of the app
Choose Settings, then go to Notifications and activity make sure that these are on and configured as you expect to see them.

Note: Channel notifications are OFF by default when you create a new channel.