Operate Alexa Everywhere Group by Service

Configuration
1

Hi,

I am desperately trying to use the multiroom group stored in Alexa for playback:

service: media_player.play_media
data: 
  entity_id: media_player.house
  media_content_type: TUNEIN
  media_content_id: 's213886'

Unfortunately without success. Nothing happens. However, if I use an Echo Dot alone it works. If I control the Multiroom grouper via Lovelace element it also works. What am I doing wrong or what is the Lovelace control doing right?