MQTT sensor no longer working

HA 0.99.3 - was working, now not.
mqtt payload is:
home/rtl_433 {"time" : "2019-10-07 16:48:06", "model" : "Acurite tower sensor", "id" : 11794, "channel" : "A", "battery_low" : 0, "temperature_C" : 26.200, "humidity" : 53}

the sensor.yaml is:

- platform: mqtt
#'acurite/temp'
  state_topic: "home/rtl_433"
  name: "Indoor Temp"
  unit_of_measurement: '°C'
  value_template: >
    {% if value_json is defined and value_json.sensor_id == 11794 %}
      {{ value_json.temperature_C }}
    {% else %}
      {{ states('sensor.indoor_temp') }}
    {% endif %}

getting unknown as a result - it did work (HA 0.99)

Your payload is

"id" : 11794

But you’re looking for

value_json.sensor_id

Shouldn’t you be looking for “id” not “sensor_id”?

yep
but, I got an error about an hour ago when I tried that.
However, at the moment - working.
Wonder what changed - the sensor.yaml file hasn’t changed in 2 years!!