MQTT light : inactive at boot / restart

Hi

I’m experiencing strange behaviour for MQTT lights I configured in H.A.

I updated everything today, nothing changes : after a restart, the MQTT lights are “inactive” in lovelace UI, and sending a “turn_on” service call with brightness value does nothing at all. or more specifically : id DOES send brightness command payload over mqtt, but the light entity in home assistant remains “inactive”.

If I go to developpers tab and look for the light’s state, this is what is returned :

supported_color_modes:
  - brightness
friendly_name: Chauffage Jade
supported_features: 0

I’m sending service actions in Lovelace with a custom:state-switch card, and more specifically :

              - icon: mdi:leaf
                tap_action:
                  action: call-service
                  service: light.turn_on
                  service_data:
                    brightness: 64
                    entity_id: light.chauffage_jade
                entity: sensor.etat_chauffage_chambre_jade
                layout: icon
                state_styles:
                  eco:
                    icon:
                      color: '#66bb6a'

^^ this does NOT activate the light whereas …

              - icon: mdi:weather-sunny
                tap_action:
                  action: call-service
                  service: light.turn_on
                  service_data:
                    brightness: 255
                    entity_id: light.chauffage_jade
                entity: sensor.etat_chauffage_chambre_jade
                layout: icon
                state_styles:
                  confort:
                    icon:
                      color: '#FFC107'

^^ this DOES activate the light and then it works as expected and shows this state, with a brightness element :

supported_color_modes:
  - brightness
color_mode: brightness
brightness: 64
friendly_name: Chauffage chambre jade
supported_features: 0

here is a relevant config (I have 2, they behave the same) , I’ve tried several things with/without availability_topic (and published “retained” payload), if anyone has a clue please ? Am I missing something in the docs ? (I’m trying to control a Qubino flush pilot controled by a openhab zwave installation, as long as I cannot find time to migrate everything from openhab and that zwavejs-to-mqtt does not recognize the qubino properly):

light:
  - platform: mqtt
    name: "Chauffage Bureau A"
    command_topic: "chauffages/bureauA/switch"
    state_topic: "chauffages/bureauA/status"
    state_value_template: >
      {% if value == 'ON' %}
        ON
      {% else %}
        OFF
      {% endif %}
    brightness_state_topic: 'chauffages/bureauA/OHoutbound'
    brightness_command_topic: "chauffages/bureauA/OHinbound"
    brightness_scale: 100
    on_command_type: "brightness"
    retain: true
    payload_on: "ON"
    payload_off: "ECO"
    availability_topic: "chauffages/always_available"
    payload_available: "1"
    payload_not_available: "0"