Hello, johnfalconer1948.
That's not expected behavior, so let's check a few things here:
- First, make sure the app supports notifications, then go to Settings > Notifications and make sure that 'Allow Notifications' is on.
- If it is on but you are not getting notified, check that Banners is turned on under Settings > Notifications.
- Check that the mute switch is not toggled on the side of the iPhone.
- Double-check that you are signed in with your Apple ID at the top of the Settings screen.
- If you navigate to Settings > General > Date & Time, is that set to ‘Set Automatically’? If not, please correct that.
- If you use an Apple Watch, please note that the notifications will go to your iPhone or your watch, but not both: Notifications on your Apple Watch - Apple Support.
- See if you have any active Focus states in use on the iPhone. Learn more here: Use Do Not Disturb with Focus on your iPhone or iPad - Apple Support.
- If this is only affecting specific Messages threads, please check that your thread is not muted: Leave a group text message thread on your iPhone or iPad - Apple Support.
- Under Settings > Sounds & Haptics, check that you have an Apple-created tone selected for the alert sound.
- If you use a VPN, please disable that temporarily.
Let us know if we can help with anything else at all or if this doesn't settle your issue. Thanks and have a fabulous day!