Spotify in combination with chromecast

I have added the following script:

  spotifyweeklyshuffle:
alias: 'Spotify Playlist Mix der Woche zufällig abspielen'
sequence:
  - service: media_player.shuffle_set
    data: 
      entity_id: media_player.spotify
      shuffle: 'true'
  - service: media_player.play_media
    data_template:
      entity_id: media_player.wohnung
      media_content_id: 'spotify:user:spotify:playlist:37i9dQZEVXcKMHncdFiqQ5'
      media_content_type: 'playlist'

but the only thing I can hear on my Google Home Mini is a short “bling” sound and then nothing happens. If I change the media_content_id to a mp4 stream and media_content_type to audio/mp4 it works as it should.
What is the problem with a Spotify playlist here?