Screen Time error after iOS 18 update (presumed to be a software bug)

Device 1: Parent iPhone iOS 18.0

Device 2: Child iPhone iOS 18.0

Device 3: Child iPad iOS 18.0

Screen Time was set to 5.5 hours per day and used.

1) On September 26, the child used the phone for about 31 minutes a day, but the phone usage time was 7 hours and 47 minutes.

2) The graph for app and website activity and the most-used app time are different.

The graph for app and website activity shows 7 hours and 47 minutes, and when the most-used app usage time is added, the least usage is recorded in single-digit seconds.

3) 7 hours and 10 minutes not confirmed in app and website activity (black and white bars, gray bars filled from 8:00 to 3:00 PM.

(The time was during class, so the school collected the phone.)

It's not just September 26, but the same phenomenon has been occurring since last weekend when the iso was updated.

4) Even though screen time (downtime off, app usage time off) was turned on for device 1, screen time restrictions were set for devices 2 and 3, so the app cannot be used.

5) There is no problem with the screen time settings, but devices 2 and 3 are not unlocked.

All evening, changing the settings and repeatedly turning the system off/on

I contacted Apple Customer Service (080-333-4000) and asked if Screen Time could not be turned off, and there was no problem with the settings. They replied

Apple Customer Service said there may be an iCloud sync issue, and that there may be a network issue with devices 2 and 3.

I confirmed with the customer that iCloud sync is Apple's management area and that the network is both Wi-Fi and cellular.

However, devices 2 and 3 still have screen time restrictions.

6) It is presumed to be an Apple iso software error, so I reported the case to Apple headquarters and asked them to check this issue (they did not give a clear answer about whether they would or would not do this, and gave the impression that it was something they could not do.)

7) After talking to an Apple customer service representative (22:00), I changed the screen time settings for devices 1, 2, and 3 in front of me for an hour, and turned the three devices off and on repeatedly.

→ Not resolved.

8) At around 23:00, I gave up (although I shouldn't have) and 'Stop screen time management'.

→ Then, the screen time restrictions were lifted and devices 2 and 3 could be used.

The purpose of my iPhone is to manage my minor child's devices. There is no other purpose. (I'm using iso, android respectively)

For reference, I've been using iPhone for the past 2 years, and the screen time has been mixed up more than once or twice. Let's do it right.

Ask Apple.

1) Is the screen time of iso 18 perfect?