There is an iOS 7.x bug that cause the device t properly increment badge but stop displaying alert and playing sound for push notification for an app.

To force iOS 7.x to reset its state, you need to:

  • Open iOS 7 Preferences -> Notification Center.
  • Go to the app facing this bug (For example Boxcar).
  • Disable all toggles and reenable them again.
Voilà, you should receive sound and alerts again.