Family Sharing Screen Time device stuck

The new device for the child is not appearing in parental controls.

I had previously set up Family Sharing Screen Time for both my child's iPhone and mine. I could monitor and manage my child's iPhone from my own device. I hold the organiser account in Family Sharing, while my child has a child's account.

A week ago, I had to reset my child's iPhone, and since then, the device can no longer be managed from my iPhone (or Mac). To better understand the situation, I renamed my child’s iPhone and noticed that the old name still appears in Family Sharing on the Mac. However, in the child’s Apple ID account and in the Locator, the new name is displayed, with the old name appearing nowhere else except in Family Sharing on the Mac. Additionally, in Screen Time on my phone, there are no active devices listed under my child’s account.

I can set up parental controls directly on the child's iPhone, but I’m very keen to restore remote management.

I’ve already performed a reset and re-linked the child’s phone to their Apple ID, unlinked and re-linked the phone again, restarted all involved devices, and toggled parental controls on and off in various sequences: child-parent, parent-child, child without parent, and parent without child.

My iPhone iOS 17.6.1

Child's iPhone 12.5.7 (I am aware that this version is outdated, yet it still supports Family Sharing Screen Time. This is indirectly confirmed by the fact that the settings were functioning successfully before the reset of my child's iPhone.)

Any suggestions would be greatly appreciated.