Media Player Template and Set Volume doesnt work

Configuration
1

Hello, everyone.

Currently I am trying to create a player with the Custom Media_Player_Template.

Almost everything works as it should, but what I can’t get right is the volume control.
I have now tried all the versions that I could find here in the forum :confused:
My config currently looks like this:

platform: media_player_template
media_players:
  playstation_5:
    friendly_name: Playstation 5
    device_class: tv
    unique_id: media.player.playstation_5
    title_template: "{{ state_attr('sensor.ps5_753_activity', 'title_name') }}"
    current_source_template: "{{ state_attr('sensor.ps5_753_activity', 'title_name') }}"
    current_volume_template: "{{ state_attr('media_player.marantz', 'volume_level') }}"
    current_is_muted_template: "{{ state_attr('media_player.marantz', 'is_volume_muted') }}"
    media_image_url_template: >
      {% if states('sensor.ps5_753_activity') == "playing" %}
        {{ state_attr('sensor.ps5_753_activity', 'title_image') }}
      {% else %}
        off
      {% endif %}
    value_template: "{{ states('switch.ps5_753_power') }}"
    turn_on:
      service: switch.turn_on
      data:
        entity_id: switch.ps5_753_power
    turn_off:
      service: switch.turn_on
      data:
        entity_id: switch.ps5_753_power
    volume_up:
      service: media_player.volume_up
      data:
        entity_id: media_player.marantz
    volume_down:
      service: media_player.volume_down
      data:
        entity_id: media_player.marantz
    set_volume:
      service: media_player.volume_set
      data_template:
        volume_level: "{{ state_attr('media_player.playstation_5', 'volume_level') | float + 0.05 }}"
      target:
        entity_id: media_player.marantz

With this config I can turn up the volume step by step, but turning it down does not work.

My goal is to have my own media player for the PS5. The volume is normally controlled via the AV receiver “Marantz”, but should also work via the volume function of the PS5 media player.

Currently, I am really at a loss where my error lies.

Anybody have an idea?

thanks