Notifications suddenly stopped working

Help!

I have an iPhone12 pro. Suddenly the sound and ‘icon’? notifications for messenger, WhatsApp and Snapchat have stopped! I can only tell that a message has come through when I’ve opened the app.

I’ve checked the settings are on, banner style, I’ve turned notifications off, then restarted the phone, that didn’t work. I’ve changed the sounds selected, rebooted several times, updated all apps and have the recent update on the phone 17.4.1 …. what is left to do?

The only thing I haven’t tried is deleting the apps then reloading them. I’m not keen to do this as it will lose all the history ….

Any new suggestions would be very gratefully received as this is extremely frustrating!