Tasmota - Sonoff Mini

I got my first sonoff mini which I immediately flashed with tasmota. In HA I configured it like this:

- platform: mqtt
    name: 'Badezimmer Gross'
    state_topic: "myhome/badezimmergross/sonoff/RESULT"
    value_template: "{{ value_json.POWER }}"
    command_topic: "myhome/badezimmergross/sonoff/POWER"
    payload_on: "ON"
    payload_off: "OFF"
    availability_topic: "myhome/badezimmergross/sonoff/LWT"
    payload_available: "Online"
    payload_not_available: "Offline"
    qos: 1
    retain: true

Now the problem, I can toggle the sonoff mini in the tasmota web ui and it’s synched back to HA, i.e it turns off / on. However, I can not control the sonoff mini from HA. I can tap the switch but nothing happens, but I can see the message in MQTT, but not in the tasmota log.

What could cause this weird behavior?