Stop making changes! v16.38 stopped working with my All Accounts. This is becoming more annoying as time goes on.
Used to be able to see all mail accounts in ALL ACCOUNTS folder. Now it shows some not all. Really irritating.
Davis Hunt commented
I used my All Accounts with the current release version of Outlook. The New Outlook does not allow this feature to be enabled for some reason. I understand from Tech Support that All Accounts is limited to those set up with Microsoft Sync technology. I have one of those accounts and about 20 IMAP accounts. I have to have All Accounts include "All" of my "Accounts". Hence the name for this feature, "All Accounts". Again, this worked in the current release version of Outlook.