iOS 15 Beta - Custom notification sound no longer working

Below is my code. It has always worked fine. Now in iOS 15 it no longer plays the custom notification sound, it plays the default tri-tone sound when the notification fires. Everything else is working fine.

let notificationContent = UNMutableNotificationContent()
let customNotificationSound = defaults.string(forKey: "notificationSound")

notificationContent.title = "Notification Title"
notificationContent.subtitle = "Notification Subtitle"

notificationContent.body = "Notification Body"
notificationContent.sound = UNNotificationSound(named: UNNotificationSoundName(rawValue: "\(customNotificationSound ?? "default").m4a"))


notificationtriggerDate = Calendar.current.dateComponents([.day,.month,.year,.hour,.minute,.second,], from: notificationTriggerTime)
let notificationtrigger = UNCalendarNotificationTrigger(dateMatching: notificationtriggerDate, repeats: false)
let notificationrequest = UNNotificationRequest(identifier: UUID().uuidString, content: notificationContent, trigger: notificationtrigger)

center.add(notificationrequest)
{ (error) in
    
    if error != nil {
        print(error as Any)
    }
}
}