Thanks for your support. I've resolved the issue. The problem was caused by conflicting entitlements. When the App Group capability was added, a new entitlements file was generated. To fix this, I merged the App Group information into the existing entitlements file, and the problem is now resolved.

Main app bundle identifier: in.xxx.app Intent extension identifier: in.xxx.app.MuteIntent App group: group.in.xxxx.shared I have save value A in Main App target and B in Intent extension target against the same key and re-run the app. Both target have its own value which I saved previously. It means UserDefaults in not shared between targets. Also tested same behaviour with Message extension where UserDefaults sharing working fine. xcode: 16.2 iOS simulator: iphone 16 pro 18.1 Is it limitation with Intent extension (Siri)?

Yeah, App groups are defined in both target.

Does it supports any other CarPlay category ex: Navigation etc?