Missing MAPI profile
You have created a MAPI profile but cannot see it e.g. in MFCMAPI.
MAPI profiles are visible only to users for which they were created. If you created a MAPI profile for a mailbox of, let us say User-A, its MAPI profile will not be visible when browsing MAPI profiles e.g. with MFCMAPI tool run under User-B.
You may stumble upon this problem for example, when using CodeTwo Exchange Migration or CodeTwo Office 365 Migration. Suppose you configured a MAPI source server connection to use a different mailbox than the one that belongs to your user. The software supports such configuration. But, when troubleshooting any issues with the software you might be checking MAPI profiles by using MFCMAPI tool and be surprised that you cannot see the profile that you just created.
Be advised that this is normal behavior of Windows and MAPI libraries and cannot be worked around any other way than by logging in to Windows with other users' accounts and checking their profiles then.