^ That's for the enumeration, the documentation for MPNowPlayingInfoCenter's playbackState instance property specifies it's only for MacOS under Discussion: "This property only applies to macOS. You must set this property every time the app begins or halts playback, otherwise remote control functionality may not work as expected." https://developer.apple.com/documentation/mediaplayer/mpnowplayinginfocenter/2588243-playbackstate

I wouldn't expect calling retrieveConnectedPeripherals(withServices:) or retrievePeripherals(withIdentifiers:) on the watch to be able to retrieve peripherals connected via ASK on the phone, was that the case when both apps were using Core Bluetooth?