iPad Screen Time not pausing as expected

On my child’s iPad I have his screen time monitored. So when he get it let’s say I let him have 1hr. He plays for 30mins. I need him to come help me. He exits what he was doing. *we have tried both completely clocking in the background also with no change* He locks the screen. He comes back 15mins later and plays. After another 15mins of h playing it will say that his time is up. I can’t figure anything out.