My iPhone is no longer notifying me when text messages arrive

There are a few reasons why you might not be getting notifications on your iPhone. Here are some of the most common causes:

• Do Not Disturb mode is turned on. Do Not Disturb mode silences all notifications, so make sure it's turned off. You can do this by swiping down from the top of your screen and tapping the crescent moon icon.
• You're in a Focus mode. Focus modes are like Do Not Disturb mode, but they can be customized to block notifications from specific apps or people. To check if you're in a Focus mode, swipe down from the top of your screen and tap the Focus icon.
• You've turned off notifications for a specific app. You can turn off notifications for individual apps in the Settings app. To do this, go to Settings > Notifications and scroll down to the app you want to change. Toggle the Allow Notifications switch to the off position.
• Your iPhone is in Airplane mode. Airplane mode turns off all wireless connections, including cellular data and Wi-Fi. This means that you won't be able to receive notifications if your iPhone is in Airplane mode.
• Your iPhone is not connected to the internet. If your iPhone is not connected to the internet, you won't be able to receive notifications from apps that need to connect to the internet to send notifications.
• Your iPhone is not up to date. Sometimes, software updates can fix bugs that can cause notification problems. Make sure your iPhone is up to date by going to Settings > General > Software Update.

If you've checked all of these things and you're still not getting notifications, you can try restarting your iPhone. If that doesn't work, you can contact Apple support for help.

Have you enabled Scheduled Summary?

Settings > Notifications > [Select the App that you are having trouble receiving immediate notifications]

See the pic below for a few examples. Please select immediate delivery.

Go to Settings and tap Notifications. Select an app under Notification Style. Under Alerts, choose the alert style that you want. If you turn on Allow Notifications, choose when you want the notifications delivered — immediately or in the scheduled notification summary.

Use notifications on your iPhone, iPad, and iPod touch

Change notification settings on iPhone

1. Go to Settings > Notifications.
2. To schedule a notifications summary, tap Scheduled Summary, then turn on Scheduled Summary. ... 
3. To choose when you want most notification previews to appear, tap Show Previews, select an option—Always, When Unlocked, or Never—then tap.

More items...

Change notification settings on iPhone - Apple Support (IN)

You can allow access to Notification Center on the Lock Screen. Go to Settings > Face ID & Passcode (on an iPhone with Face ID) or Touch ID & Passcode (on other iPhone models). Enter your passcode. Scroll down and turn on Notification Center (below Allow Access When Locked).

View and respond to notifications on iPhone - Apple Support (IN)

Here are some additional tips for troubleshooting notification problems on your iPhone:

• Make sure that your iPhone is not in silent mode.
• Check the notification settings for individual apps to make sure that they are turned on.
• Make sure that your iPhone is connected to a Wi-Fi network or cellular data network.
• Restart your iPhone.
• Update your iPhone to the latest version of iOS.
• Contact Apple support for help.

Seeing as I had had the same issue and couldn't find a fix, I thought I would add my eventual fix!

It is relevant to people with Apple Watches:

Obviously at this stage I will assume all notifications/ focus/ Face ID/ Touch ID are all in check, then if still an issue, go to your Apple Watch app.

TAP:

Notifications

TAPS:

Messages

TICK:

Send to Notification Centre ✔️

Et Voila ! 🙂👍

Hope it works!!

None of these suggestions have helped. I still do not receive text alerts when phone is locked.

All suggestion above show not paying attention to the issue at all . I am having the same issue . From the mass amount of posts in the forums there are a huge amount of others with the same issue . I am close to selling my iPhone and going back to Samsung . I did that years ago because of getting screwed over by apple too many times . The issue : when phone is locked texts messages do not alert with a sound . (Only texts) this was broken by apple a few months ago . You read that right . MONTHS . There is no excuse for not fixing this already . They have about a month and once again it’s back to a Samsung phone. This issue seems related to having apples headphones and or Apple Watch connected with Bluetooth . I can have the headphones and Apple Watch off and still only text sound not working . Phone call sound works perfectly . For now , as annoying as it is , turn off Bluetooth in settings . Not the pull down menu . Turn it off in settings .

The little red light doesn’t come on when messages arrives

My I phone is not notifying me when I receive a text message