Thanks for submitting. It was a certificate that needed to be replaced. Should now work.
Tip 2. Check whether "Do Not Disturb" is activated. If this feature is enabled on Settings app, calls and alerts will be silenced while your iPhone locked.
Tip 3. Check whether you turn on the notifications for the apps by going to Settings > Notifications. If you turn off notifications for some apps, it won't notice you the apps' news.
Tip 4. Check whether the network is working in a good condition. If it isn't, apps won't update the news and send notifications. Just re-connect your Wi-Fi or Cellular network. Or reset network settings.
Tip 5. You can restart your device, which is one of basic tips to fix any iOS issues.
Did you give permission to retrieve push notifications? These are 2 parts - when you open app it just fetches the messages from us. The push messages get send over apples system and only work if they are allowed.