We need clarification about whether remote audio SharePlay using GroupActivities is supported while an iPhone is connected to CarPlay. Our audiobook app uses GroupActivities with activity metadata set to .listenTogether. SharePlay works normally between two iPhones without CarPlay. Across seven controlled comparisons on two iPhones running iOS 27.0.1, we observed: Connecting CarPlay during a working SharePlay session causes the connected phone’s session to invalidate and GroupStateObserver.isEligibleForGroupSession to become false. With CarPlay already connected, the system SharePlay UI displays the session and allows an apparent join, but our app receives no GroupSession. This occurs whether the CarPlay phone is host or receiver and reproduces on either phone. It also occurs when audio remains routed to Bluetooth headphones rather than CarPlay. We observed the same user-facing behavior when testing Spotify’s remote SharePlay. Is this expected platform behavior, a known issue, or an application configuration requirement? If this combination is supported, what public API or configuration should applications use? If this combination is not supported, is there a supported path to allow synchronous remote audio while on carplay? We are asking about remote GroupActivities SharePlay, not Apple Music’s in-car passenger SharePlay feature.