I have searched and found no results regarding this extremely annoying issue. Essentially, I have no new emails in my inbox and yet I receive the attached notification icon in my taskbar accompanied by a notification sound (as if I have received a new email).
When clicked on, it opens Outlook into the inbox. The notification persists until I click on EITHER of my two O365 groups.
This is very distracting to my work as I have urgent and timely emails to reply to, so always click on it as soon as it appears. This notification recurs every 1-10 minutes.
I have left and then rejoined both groups without change. I have rebuilt mail profile, and local PC profile without success. And I have discovered this issue follows me to other computers! My home PC, and multiple work PCs have exactly the same issue! I have disabled 'Follow in inbox' and other notification settings. We depend on these O365 groups for our Teams channels and only I am having this issue...