Screentime, web and app activity of my son doesn't update anymore

My son is part of my family on my iPhone and I am listed as his guardian. Since a couple of weeks, I can't see his screentime/app and webactivity anymore. I get the message:

Screentime for iPhone of X is already not available for 7 days. Check that the device i s connected to internet and logged in to iCloud with the Apple Account of X.

I checked and my son is indeed logged into iCloud with his Apple Account (i can see that he is sharing in my iCloud storage).

Another issue I have is that I get extra screentime requests from my son on my iPAd and my macbook, but not on my iPhone (i lost the 'family group chat' in messages where these requests used to come in. This group is still visible on my iPad and macbook. If I ok the request on the iPad or macbook, my son doesn't receive the extra screentime though.

Can someone help me with this? Both with the invisible screentime and with the missing/not working requests?

thanks in advance