Randomly not receiving Time request from my child in Apple Parental Control (Screen Time)

Screen Time generally works fine, but sometimes I don’t receive my child’s requests for more screen or app time. Normally, these requests come through iMessage, but in certain situations, I don’t get them at all — not in iMessage or in the Screen Time app.

The internet connection seems fine because I still receive her WhatsApp messages when this happens.

Any idea what might be causing this?