I'm having the same problem and seeing that this question was posted 5 month ago doesn't induce hope to find a fix. The users where able to subscribe, later the app logs a com.apple.storekit [Default] Failed in XPC service while enumerating transactions for IterationType.current: Error Domain=NSCocoaErrorDomain Code=4097 "connection to service named com.apple.storekitagent" UserInfo={NSDebugDescription=connection to service named com.apple.storekitagent} and purchases are not available anymore. I read that if the user deletes a com.apple.storekitagent folder somewhere and restarts the Mac, it works again but that's not even a good temporary solution.

I ran into the same problem after setting up my project on my new MBA M2. After multiple restarts, I went through the System Preferences > Security & Privacy and noticed by accident that I hadn't checked the box under Developer Tools for the Terminal.app. After that, Xcode crashed when opening projects. Short panic and a restart later, the project opened again and it told me that my MBA is not registered as a device in the Provisioning Profile. After repairing, everything works now... Maybe that helps someone...