Changing entity_picture in Universal Media Player

Hey all,

I’ve created an universal media player to unite a couple of sources, one of which is Jellyfin.
Jellyfin has two entity pictures attributes, entity_picture and entity_picture_local, and apparently only the entity_picture_local format works on the mobile app.
In order to deal with this i tried to overide the attribute in entity_picture on the Universal Media Player entity, following the documentations ( media_player.the_entity|the_attribute ) but it doesn’t seem to work.
Is this expected behaviour? Can anyone suggest a possible work-around?

    platform: universal
    name: Universal Shield
    unique_id: media_player.universal_shield
    children:
      - media_player.plex_plex_for_android_tv_shield_android_tv
      - media_player.jelly_shield
      - media_player.shield_adb
    active_child_template: >
      {% if is_state('media_player.spotify','playing') and 
      is_state_attr('media_player.spotify', 'source', 'SHIELD') %}
         media_player.spotify
      {% elif is_state_attr('media_player.shield_adb', 'source', 'Google Cast') %}
         media_player.shield_5
      {% else %}
      {% endif %}
    attributes:
        volume_level: media_player.str_dn1080|volume_level
        entity_picture: 'media_player.spotify|entity_picture'
    commands:
        volume_up:
            action: media_player.volume_up
            data:
              entity_id: media_player.str_dn1080
        volume_down:
            action: media_player.volume_down
            data:
              entity_id: media_player.str_dn1080
        volume_set:
            action: media_player.volume_set
            target:
              entity_id: media_player.str_dn1080
            data:
              volume_level: "{{ volume_level }}"
        media_play:
            action: media_player.media_play
            data:
              entity_id: remote.shield_2
        media_pause:
            action: media_player.media_pause
            data:
              entity_id: remote.shield_2
        media_play_pause:
            action: media_player.media_play_pause
            data:
              entity_id: media_player.shield_2

Thanks for the help!