MQTT sensor "payload_not_available"

Configuration
1

Could you please check what is wrong with my MQTT payload_not_available configuration?

I run the HA MQTT broker and receiving data from WeeWx via MQTT. The MQTT topics arrive in time and are correct. But as the sensor is sometimes disconnected, I want to mark this with “payload_not_available”. Here is my configuration.yaml

- platform: mqtt
  name: "Wind Speed"
  icon: mdi:weather-windy
  state_topic: "weewx/windSpeed_kph"
  value_template: '{{ value | round(1) }}'
  unit_of_measurement: "km/h"
  availability:
    - topic: "weewx/windLinkStatus"
  payload_available: "0"
  payload_not_available: "1"

But the Wind Speed data is not available

Bildschirmfoto 2021-01-05 um 20.32.19
Bildschirmfoto 2021-01-05 um 20.32.191290×650 17.4 KB

even though the weewx/windLinkStatus changes:

Bildschirmfoto 2021-01-05 um 20.28.55
Bildschirmfoto 2021-01-05 um 20.28.551228×1474 82.7 KB

the straight forward configuration for the same sensor but different attribute, delivers data:

- platform: mqtt
  name: "Wind gust Speed"
  icon: mdi:weather-windy-variant
  state_topic: "weewx/windGust_kph"
  value_template: '{{ value | round(1) }}'
  unit_of_measurement: "km/h"

but of course is not capturing missing data.

What do I have to do different in the availability configuration? Any help welcome…

2

Can somebody point me to the code or file where I can research and test myself. I did not manage to find myself…