If the iPhone is not in "sleep" and you still have the messages app open, you will not get a notification. If the phone is locked, or you have closed the messages app, you should get whatever notification you have set for messages in notification. Go to Settings, Notifications, Messages and set how you want to be notified. Also, you can go to Settings, Sounds, and make sure you have a sound assigned to Messages.
It seems to ONLY happen when I put it to sleep after sending off a text. I can leave the app open or close it and it won't notifiy me. If someone just sends me a text when it's sleep, then I get notified.
It must be some setting? I've checked all the notification, messaging settings that I can think of.
Please help me!!
Maybe a soft or hard reset? Not sure how to do that but maybe that's what it will take?