iPhone 11 screen doesn’t light up when I receive a notification

I have revived my new iPhone 11 it’s up and running and now I’ve realised that when I get a notification e.g a text the screen doesn’t light up, the phone vibrates or makes a sound but no light. I have got my do not disturb off and I have been through all my notification settings there all on the correct settings I have matched them up with my sisters who’s works fine. I’m looking for more suggestions before I decide I have a faulty phone screen.