I've reviewed both the tenant and mailbox settings, and both show Focused Inbox as enabled. I don't believe this to be the culprit because Focused Inbox is confirmed working for at least one of my co-workers, so the problem seems to be limited to my mailbox. (2) I enabled Modern Authentication in our Exchange Online tenant yesterday. I only mention this because I saw someone else report a similar problem that started after installing or upgrading his Mac client. (1) A few days ago, I uninstalled and reinstalled the Office 2016 suite on my Macbook, and installed the latest version from our Office 2016 tenant (E3 corporate license). So, two things have occurred recently, which may have affected this functionality. However, it seems to have stopped working, in all clients! It had been present and working in my Mac Outlook 2016 client, as well as in both OWA and iOS Outlook clients, just missing from the Windows Outlook 2016 client.

Finally got Focused Inbox to appear in my Windows Outlook 2016 client yesterday, after finally enabling Modern Authentication in our Exchange Online tenant.

My show focused inbox disappeared