In the classic Outlook I can add Inbox folders of shared mailboxes to Favorites, easily detecting and accessing new emails sent to any of mailboxes I manage. In the new Monarch Outlook, this is no l...
I agree that this is a showstopper for the New Outlook.
However - I do believe that this is on the M365 Roadmap:
https://www.microsoft.com/en/microsoft-365/roadmap?filters=Outlook%2CIn%20development&searchterms=375635
By doing this it will (hopefully) be possible to place the Inbox in Favourites also in the new client.