Unwanted camera silence in iPhone XR

I am unable to get the camera to ‘click’ when the shutter is pressed. I've googled and confirmed that the volume is up, the mute button is off, and Live is off. Other sounds (ringtone, lock screen etc) all work as expected. Does anyone have any suggestions as to why there is no sound with the camera?

Is the problem related to phone not ringing on some incoming calls (intermittent problem)- straight to VM - under same conditions: volume up and mute button is off?

thanks