Windows 10: Specific apps not showing up in notifications & actions settings panel

I recently installed the Windows 10 upgrade on my laptop, but the action center and PC notification features are not working for me. I am receiving no notification banners for the twitter, facebook, alarm, etc apps. The notification options within the apps themselves are turned on, but some are not showing up in the settings menu. (See attached images)

I tried running an app registry key reset found here, but that did not solve the problem, and tried running "sfc /scannow" in the command prompt to check for corrupted files but came up with no errors.

The apps that are missing in the system settings notification menu are twitter, alarms, duolingo, facebook, and pretty much everything else except the mail and calendar apps. How do I add them, or at least get my computer to recognize that they exist?

:)

 

Pop Ups seem to be disabled in Windows 10

Is this pop up for a specific application, if so, which is it?

All notifications are managed in Start > Settings > System > Notifications & quick actions

Scroll down and make sure it is on for the app you are referring to.

 

Apps Missing From "Get notifications from these senders"

Under Settings>System>Notifications & actions>Get notifications from these senders

there aren't any senders/apps that show up. All that shows is the timer, a series of rotating dots, that indicate that the app is looking for senders. The Mail app is one of the apps that I expect to see (it has been set up to send notifications).

How can I reinstall, or fix the Notifications to show apps?