Private ble not detect iPhone when lock screen

Configuration
1

I have 3 iPhone in different model.
iPhone 13 Pro Max, 14 Pro Max and 15 Pro Max.
Only 14 Pro max will show not_home when screen is locked.

Not sure if it’s because 13 PM and 15 PM both connected to an Apple Watch. So it will continue advertising ble beacon.

Anyone can help on how should I troubleshoot this?

Btw, I have checked handoff and restart the device.

2

Not really a fan of Apple devices, so this is just a possible hint.
Check that the phones have the same rights, like running apps in the background, use location in the background (Bluetooth and location is often linked together) and use network data in the background.

3

I’m experiencing the same issue with my iPhone 13 Mini and two iPhone 11. Does anyone have any solutions as to how to keep the iPhone from disappearing when it’s not in use?