Apple claims that it has discovered an issue in which the unlock with Apple Watch feature may not work on its iPhone 13 devices. The problem is described in a new note on Apple's support page:
If you attempt to unlock your iPhone with a mask on, you may see Unable To Communicate With Apple Watch. Or you may not be able set up Unlock with Apple Watch.
Users on the r/AppleWatch Reddit forum began reporting this problem Friday. Some reported that they were able use the Watch unlock feature with other iPhone models including the iPhone 11 Max.
Apple released iOS 14.5, which included the ability to unlock iPhones that use Face ID and paired Apple Watches earlier this year. This is useful in times of pandemics where face masks can be recommended in public places. Face ID will not recognize you if this happens. This feature is compatible with iPhone X and older models. Both the iPhone and Watch must have Bluetooth and wi-fi enabled. For the feature to work, the Watch must have wrist detection enabled and passcode protected. It also needs to be unlocked and on your wrist.
Apple did not say what was causing the iPhone 13 device problem, only that it would be addressed in an upcoming software upgrade. However, Apple does not know when the update will be released. Support page notes recommends turning off unlock with Apple Watch and using your passcode for unlocking your iPhone 13 while it is masked.
