You aren't alone with this. Since I got cyan on my 1520 I am not getting banner notifications for fitbit tracker and other apps I previously got. I was on the developers preview so I had to downgrade to 8.0 to get cyan. After I got it I used my backup on DP 8.1 to restore. I have uninstalled and reinstalled the apps and they don't show up in notifications or actions. I have a 635 with cyan so I will check that to see if it is an 8.1 thing. I don't believe so since it worked on the DP.
EDIT:
After checking my 635, I saw more apps in the notifications + actions. I did a search and found this: social.msdn.microsoft.com/Forums/en-US/20dd9ba8-2cbb-4733-be42-63770bb407ea/missing-apps-in-notificationsactions-settings-page?forum=winphoneosissues (I can't post links so add the http to the front of it)
Basically,
the extra apps do not show up until they actually send a notification to the action center. once they do, their names are added to the list in the settings page, and you can change their notification settings. until then, they are not in settings, so you cannot control their notifications beyond what can be done from within the app.
I forced an message through Facebook Messenger and the next thing I know it showed up in Notifications + Actions. I have Kik on the 635 and so it was showing there as well. My Fitbit Tracker still isn't showing notifications on either device so I'm going to contact those developers.
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