Hi @barneythecat, that's odd. Please try the following and let me know:
1. Swipe down to your Quick Panel Settings > ensure 'Sensors Off' is off (should be greyed out, not blue)
2. Check if a 3rd party app may be preventing it from opening:
Settings > Biometrics and security > Other security settings > Device admin apps. From here you can see which apps may be blocking the use of the camera.
