Portrait mode iPhone X not working

I have been able to take photos in portrait mode and recently it has stopped working. It is still able to work in ‘selfie’ mode with the front facing camera but not with the rear facing camera on the back of my phone which is the only way I really like to use the feature. It always says ‘move further away’ when someone/thing is in shot or at times, changes to say ‘place subject within 8 feet’. There has not been any damage to my phone (that I’m aware of). I thought it coincided with an update at the beginning of Jan and there has since been another update and the problem has not changed. Any ideas on how to rectify the problem would be very welcome!