Device and software: iPhone model: iPhone 15 Pro iOS 27 Public Beta 6 Build: 24A5430a BLE receivers: two independent ESP32's IRK has worked reliably on iOS 26 and past versions. Observed behavior: With the iPhone display on both BLE receivers detect advertisements that resolve correctly using the enrolled IRK. No more than 10 seconds after the display is turned off, the IRK-resolvable advertisements stop. The IRK identity returns immediately when a notification wakes the display or when I manually do. Bluetooth itself remains active while this happens. The receivers continue to see several strong advertisements from the phone with some unidentified rotating addresses. The unidentified addresses rotate periodically and cannot be associated with the enrolled IRK. Additional observations: When my Apple Watch is powered on and connected, the iPhone remains IRK-detectable while the screen is off. It stops again when watch is disconnected. Connecting Bluetooth headphones does not have the same effect. The IRK-resolvable advertisement stops even while music continues playing. Moving the affected phone between two receivers confirmed that the unidentified rotating advertisements physically followed the phone. The existing IRK remains valid because it resolves the phone again immediately whenever the display wakes. I couldnt find any intentional IRK, private-address or screen-off advertising change documented in the iOS 27 release notes or any discussions online. Has anyone else observed this on iOS 27?