After upgrading to iOS 9 yesterday, today I discovered a strange and annoying thing that I do not receive new message notifications (from neither WhatsApp nor Facebook Messenger) unless I unlock the screen first. It's like background app refresh has been turned off when in reality it hasn't. I checked from Settings and WhatsApp does have background app refresh turned on. Does anybody know any solution to this? As you can guess, it doesn't make sense to unlock the screen every few moments to check for new messages. I should be receiving new message notifications as soon as they arrive. I can tell it's got something to do with the upgrade to iOS 9 as it hasn't happened before. Thanks!