Creating a simple BBC 2 Radio lovelace panel

I’m trying to create a very simple lovelace panel using the mini-media-player HACS component. But am getting no output. Here’s my code:

type: custom:mini-media-player
entity: media_player.googlehome0851
artwork: cover
source: icon
hide:
  volume: true
toggle_power: true
volume_stateless: true
group: false
sound_mode: icon
shortcuts:
  columns: 4
  buttons:
    - name: BBC Radio 2
      type: music
      id: >-
        http://as-hls-ww-live.akamaized.net/pool_904/live/ww/bbc_radio_two/bbc_radio_two.isml/bbc_radio_two-audio%3d96000.norewind.m3u8

Clearly I’m doing something wrong but I cannot see what.