Hey there AmericanSisu,
Thanks for reaching out to Apple Support Communities. I understand you’re not able to view your children’s Screen Time usage from your device any longer. I’ll be happy to help with this.
If this feature recently stopped, make sure all devices are up to date:
Update your iPhone, iPad, or iPod touch
How to update the software on your Mac
If they are up to date, restart all devices:
Restart your iPhone
How to turn your Mac on or off
If the issue continues after that, turn off Screen Time on their devices, restart, and turn it back on. This will cause current data to be lost but may resolve this issue:
Use parental controls on your child's iPhone, iPad, and iPod touch
Regards.