MQTT auto discovery isn't working, but messages are visible

Third party integrations
2

At first glance, it looks OK. I wouldn’t normally set the entity’s state_topic to something so similar to its discovery topic but I think it should be OK.

Just for fun, try this script.

  create_entities:
    sequence:
      - service: mqtt.publish
        data:
          topic: homeassistant/binary_sensor/bathroom_door/config
          payload: >
            {
              "name":"Bathroom Door",
              "state_topic":"home/sensor1",
              "device_class":"door"
            }

Alternately, just go to Developer Tools > Services, select mqtt.publish, then set the options:

topic: homeassistant/binary_sensor/bathroom_door/config
name: Bathroom Door
state_topic: home/sensor1
device_class: door

and click CALL SERVICE.

Normally you would include retain: true so that the discovery topic and its payload are stored on the broker. This ensures that when you restart Home Assistant, the entity will be re-created (otherwise it won’t). For testing purposes, it’s not necessary (you probably don’t want this entity to persist beyond the next restart).