History Graph - MQTT Sensor / Showing last value when sensor is offline

Configuration
1

Hello!

I have several mqtt sensors and I don’t like the behaviour of the history graph card. When a sensor is offline, I would like to see NO data points. I can’t find out the right setting. It is even possible?

In the picture you see the data form a solar inverter. When the inverter/sensor is offline, HA shows a straight line. When HA is shut down, there are no data points = what I want.

Reloading the HA tab, it shows always a new data point with the last known value of the sensor. What I’m missing?

Thank you!

HA - sensor
HA - sensor2199×679 92.4 KB

Here my simple sensor setting:

mqtt:
    sensor:
       - name: "MIC Power22"
         state_topic: "energy/solar"
         unit_of_measurement: "W"
         value_template: "{{ float(value_json.MIC_Power) }}"
2

Update: I added “expire_after: 20” - but the history graph on every reload shows a data point with the actual time an the latest value.