Lovelace: Mini Media Player

If it works with the others on their default theme, then I guess it must be something on my end.

This is the code that I am using in ui-lovelace:

  - type: custom:mini-media-player
    entity: media_player.bad
    icon: 'mdi:cast'
    hide_power: true
    show_source: true
    title: Sonos Badezimmer
    more_info: false

Anything that may seem wrong here?