Notifications won't open when I click on them on Windows 10

In Windows 10, there are a number of different dialogs that control notifications.

• In Settings | Notifications & actions, you may need to turn on Get notifications from apps and other senders, as well as the switch for a specific sender.

• In Settings | Privacy | Background apps, you may need to turn on Let apps run in the background, and select specific apps to display its notifications. (This requirement may be new to Windows 10 v. 1809; I noticed after installation that Notifications was broken until background apps were enabled.)

And, as T. Lehrer said of the elements, "There may be many other [dialogs] but they haven't been discahvahd."