Any luck?
I hit this in Xcode 15 Beta 8 (also 14.3.1 (14E300c)) when trying to add a NotificationServiceExtension Target to my App/Project. This "(null)" target occurs regardless of my Deployment target (tried iOS 16.0 and 17.0). It's my top candidate as the root cause for why my NotificationServiceExtension will not attach, print anything to console, nor hit a breakpoint.
Other tactics I tried:
Ensuring the iOS deployment target and marketing version is the same for app/NotificationServiceExtension
Adding AppGroup capability to the NotificationServiceExtension and configuring for each buildEnv
Adding PN capability to the NotificationServiceExtension
Ensuring the bundleId stem of the NotificationServiceExtension matches the app