There are several reasons why you may encounter the Outlook notifications not working issue. Do not be alarmed if the outlook notification issue occurred suddenly. To begin, open the Outlook app and then choose 'File' and then 'Options.' After that, a pop-up window will appear, and you should touch on 'Mail.' There will be a 'Message arrival' area. Make sure the 'Play a sound' and 'Display a sound' choices are set on, then press 'OK.'