Build in radio browser shows no entity_picture on dashboard

Configuration
1

Hi
i start playing a stream from the HA-radio-browser to a sonos box in node red. Therefore i use the media_contend_id from the radio-browser. That works fine.

{
    "media_content_id": "x-rincon-mp3radio://http://regiocast.streamabc.net/regc-80s80smweb2517500-mp3-192-1672667?sABC=65sq9728%230%23r63s7q4pnqnrq426s1qs6sq2598667or%23&aw_0_1st.playerid=&amsparams=playerid:;skey:1711118120",
    "media_content_type": "music"
}

But the picture, that is shown in the radio-browser itself. When i call the service to play, the entity_picture attribute is shown like this:

entity_picture: "/api/media_player_proxy/media_player.sonos_flur?token=49b6e1a83c3d73b660819d8d44c598d054ace7d68f4eaa0c07cddc731309c685&cache=1b20512542b1fa1d"

when i use this in my call_service node like this:

{
    "media_content_id": "x-rincon-mp3radio://http://regiocast.streamabc.net/regc-80s80smweb2517500-mp3-192-1672667?sABC=65sq9728%230%23r63s7q4pnqnrq426s1qs6sq2598667or%23&aw_0_1st.playerid=&amsparams=playerid:;skey:1711118120",
    "media_content_type": "music",
    "entity_picture": "/api/media_player_proxy/media_player.sonos_flur?token=49b6e1a83c3d73b660819d8d44c598d054ace7d68f4eaa0c07cddc731309c685&cache=1b20512542b1fa1d"
}

it doesnt even start the stream.

So how can i set the entity_picture to be shown?

regards