iPhone missing from Screen Time on other devices

My iPhone SE 2020 doesn't appear in Screen Time on my M1 MacBook Air or iPad Air 3rd gen. All devices are signed into the same iCloud account and fully updated to the latest supported stable (i.e. non-beta) OS releases. All have 'Share Across Devices' enabled in Screen Time. The Mac and iPad appear in Screen Time on all three devices but the iPhone's data only shows up on the iPhone itself. Tried: - Toggling 'Share Across Devices', on iPhone - Toggling 'Share Across Devices', on all three devices at the same time - Toggling Screen Time on iPhone - Toggling Screen Time on all 3 devices (with all off at the same time) - Logging out of iCloud and logging back in on iPhone Edit: At the time of writing the installed OS were iOS/iPadOS 14.4.2 and macOS Big Sur 11.2.3. The issue is still present in August 2024, in iOS/iPadOS 17.5.1 and macOS Sonoma 14.5.