Hello Steve,
My name is Adebayo, thank you for getting in touch.
Please note that in the new Teams, notifications are now fully served from Teams and all notifications preferences are handled within Teams Settings.
From New Teams >> Go to Settings >> Notifications and Activity >> Ensure that Notification is toggled-on
https://learn.microsoft.com/microsoftteams/new-teams-known-issues
Please do let me know if further assistance is needed.
Kind regards, Adebayo.