Command Center / Dynamic Island missing icons and animations

hello all!

I'm setting up a really simple media player in my swiftui app.

the code is the following:

import AVFoundation
import MediaPlayer

class AudioPlayerProvider {
    private var player: AVPlayer
    
    init() {
        self.player = AVPlayer()
        self.player.automaticallyWaitsToMinimizeStalling = false
        
        self.setupAudioSession()
        self.setupRemoteCommandCenter()
    }
    
    private func setupAudioSession() {
        do {
            try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default)
            try AVAudioSession.sharedInstance().setActive(true)
        } catch {
            print("Failed to set up audio session: \(error.localizedDescription)")
        }
    }
    
    private func setupRemoteCommandCenter() {
        let commandCenter = MPRemoteCommandCenter.shared()
        
        commandCenter.playCommand.addTarget { [weak self] _ in
            guard let self = self else { return .commandFailed }
            self.play()
            return .success
        }
        
        commandCenter.pauseCommand.addTarget { [weak self] _ in
            guard let self = self else { return .commandFailed }
            self.pause()
            return .success
        }
    }
    
    func loadAudio(from urlString: String) {
        guard let url = URL(string: urlString) else { return }
        
        let asset = AVAsset(url: url)
        
        let playerItem = AVPlayerItem(asset: asset)
        
        self.player.pause()
        self.player.replaceCurrentItem(with: playerItem)
        
        NotificationCenter.default.addObserver(self, selector: #selector(self.streamFinished), name: .AVPlayerItemDidPlayToEndTime, object: self.player.currentItem)
    }
    
    func setMetadata(title: String, artist: String, duration: Double) {
        var nowPlayingInfo = [
            MPMediaItemPropertyTitle: title,
            MPMediaItemPropertyArtist: artist,
            MPMediaItemPropertyPlaybackDuration: duration,
            MPNowPlayingInfoPropertyPlaybackRate: 1.0,
           
        ] as [String: Any]
        
        MPNowPlayingInfoCenter.default().nowPlayingInfo = nowPlayingInfo
    }
    
    @objc
    private func streamFinished() {
        self.player.seek(to: .zero)
        
        try? AVAudioSession.sharedInstance().setActive(false)
        
        MPNowPlayingInfoCenter.default().playbackState = .stopped
    }
    
    func play() {
        MPNowPlayingInfoCenter.default().playbackState = .playing
            
        self.player.play()
    }
    
    func pause() {
        MPNowPlayingInfoCenter.default().playbackState = .paused
            
        self.player.pause()
    }
}

pretty scholastic.

The code works when called on views. It also shows up within the lock screen / dynamic island (when in background), but here lies the problems:

• The play/pause button do not appear neither in the Command Center nor in the dynamic island. If I tap on the position these button should show up, the command works. Just the icons are not appearing.
• the waveform animation does not animate when playing.

Many audio apps are working just fine so is my code lacking something. But I don't know why. What is missing?

Thanks in advance!