The Outlook icon is still in the Notification Area with an X in it ( ).Not being able to backup your pst-files.Gears icon in the bottom right corner in Outlook.

This file is being checked for problems.” Outlook shutdown issues are not always directly apparent but may surface via other errors or issues such as

Once this troublesome add-in is disabled or updated or the other application is closed, the problem will be gone and Outlook will close normally again. At that time, you’d usually see the outlook.exe process still running in Task Manager as well. Practically always this is caused by an add-in or another application which integrates with Outlook. It isn’t very common that Outlook doesn’t close on it’s own.