getDeliveredNotifications in UNNotificationServiceExtension failed because of missing entitlement

Hi

I've added new UNNotificationServiceExtension to my application. In the implementation of didReceiveNotificationRequest:withContentHandler: I need to go through all former notification using UNUserNotificationCenter.current().getDeliveredNotifications.

The array of notifications passed to completionHandler has always 0 elements and in the iPhone logs I can see the error: Getting delivered notifications failed because of missing entitlement.

        self.contentHandler = contentHandler
        bestAttemptContent = (request.content.mutableCopy() as? UNMutableNotificationContent)
        if let bestAttemptContent = bestAttemptContent {
            // some notification modifications here...
            contentHandler(bestAttemptContent)
        }
        UNUserNotificationCenter.current().getDeliveredNotifications { notifications in
            for notification in notifications {
                // never executes
            }
        }
    }

I have enabled push notification capabilities for the main target, both targets have set the same App Group.

Any suggestions?