Cast Plex Media to Google Chromecast not working

Hi everyone,
I’m really getting desperate by now. I have found several posts here in the forum and elsewhere on the internet, but I still can’t get the problem solved.

I have my Plex server running as an add-on in Homeassistant. Furthermore, the Plex integration is set up. If I now open my media players and try to cast an entry of a music title via “browser Media”, nothing happens. there is a bit of information in the log files, but nothing that gets me anywhere.

2024-08-29 17:10:06.977 ERROR (MainThread) [homeassistant.components.websocket_api.http.connection] [139811543948528] Unexpected exception
Traceback (most recent call last):
  File "/usr/src/homeassistant/homeassistant/components/cast/media_player.py", line 100, in wrapper
    return_value = func(self, *args, **kwargs)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/src/homeassistant/homeassistant/components/cast/media_player.py", line 558, in media_play
    media_controller.play()
  File "/usr/local/lib/python3.12/site-packages/pychromecast/controllers/media.py", line 630, in play
    response_handler.wait_response()
  File "/usr/local/lib/python3.12/site-packages/pychromecast/response_handler.py", line 54, in wait_response
    raise RequestTimeout(self._request, self._timeout)
pychromecast.error.RequestTimeout: Execution of play timed out after 10.0 s.

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/src/homeassistant/homeassistant/components/websocket_api/commands.py", line 241, in handle_call_service
    response = await hass.services.async_call(
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/src/homeassistant/homeassistant/core.py", line 2763, in async_call
    response_data = await coro
                    ^^^^^^^^^^
  File "/usr/src/homeassistant/homeassistant/core.py", line 2806, in _execute_service
    return await target(service_call)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/src/homeassistant/homeassistant/helpers/service.py", line 999, in entity_service_call
    single_response = await _handle_entity_call(
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/src/homeassistant/homeassistant/helpers/service.py", line 1071, in _handle_entity_call
    result = await task
             ^^^^^^^^^^
  File "/usr/src/homeassistant/homeassistant/components/media_player/__init__.py", line 814, in async_media_play
    await self.hass.async_add_executor_job(self.media_play)
  File "/usr/local/lib/python3.12/concurrent/futures/thread.py", line 58, in run
    result = self.fn(*self.args, **self.kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/src/homeassistant/homeassistant/components/cast/media_player.py", line 102, in wrapper
    raise HomeAssistantError(
homeassistant.exceptions.HomeAssistantError: CastMediaPlayerEntity.media_play Failed: Execution of play timed out after 10.0 s.

Do you have any ideas?