Cannot change notification settings - Settings app window vanishes when I try

If I right-click on the bell at the RH end of the taskbar, and choose "Notification settings", the Settings app window opens for a fraction of a second and then disappears.

If I open the Settings app from the Start menu, it opens as normal. I enter "notification" in the "Find a setting" search field in the app window, but when I select "Notifications & actions" from the search results, exactly the same thing happens - the Settings app window disappears. Everything else I have tried using in the Settings app works without problem, it's just the notification settings that cause the problem. Any suggestions?

Hello Nick,

Depending on which notification setting(s) you want to change, you can see if another option in the tutorial below may be available to do so instead for now.