Microsoft releases updates for Outlook which break the important IMAP feature that many people rely upon.
Instead, you will need to revert to an earlier version. If you don’t disable updates, the problem update will reinstall itself.
You can disable updates from the File menu in any Office application.
In Outlook (this is an Outlook help site after all), go to File, Office Account, Update Options and click on Disable Updates.
Next, create an appointment in your calendar for 30 days from now to remind yourself to check for updates.
The buggy patches are still being pushed out to unsuspecting customers but a fix was posted a whole month later.