I have a user that has two distinct Exchange Online accounts. We configured both in one Outlook profile. The setup runs through without any issues. However, when we open Outlook, he only sees the primary mailbox.
Both mailboxes are in different Office 365 tenants. I have tested it on other systems and they work fine and are both listed with their respective folders.
When I look through the Outlook 2016 Connection Status tool, both accounts are connected. Also, when we go into the folder list view, he can browse the public folders of the mailbox that is not listed.
Any ideas what it can be? I have re-created the profile numerous times.
Something fishy with Outlook on that machine it seems. Try running it with the /resetfolders and /resetnavpane switches. Also try it in safe mode to rule out interference from add-ins. Creating a new windows profile on the same machine might also give you a clue as to what's wrong.
I am dealing with the exact same problem, I have one user that appears to have everytyhing working correctly.
I cannot seem to duplicate that setup. When I setup the account for my other user everything (within account config) appears to be just like the functioning acount but no go, the primary mailbox appears under the email address of the second tenant.