This is what worked for me on both of my child's computer, as this issue happened on both of them.
The computers (or previous computers with the same name) were added to the family account with Windows10 long time ago. Then those were replaced/rebuilt with Win11, but somehow the devices did not get refreshed in the Family Safety.
So I cleaned up the devices in the child's accounts.
Steps:
- Log in to your account on the web: https://account.microsoft.com/
- Go to Devices -> Show all devices
- Remove all the old devices, if there's any
- Remove the device you have the issue with
- When you're asked, remove the device from the Microsoft Store section too
- Check that the device you're having this issue with is not listed anywhere
- Reboot
- Log in to the computer with your MS account again
- Check if the device is added back to you account.
9.a. If not, open Microsoft Store, go to Settings, and enable "Offline permissions"
9.b. Check again
This process will not require you to be the administrator of the family, you must do this with your own account.