Integration Templates and Utility Templates suddenly "Unavailable"

Hello Tom,
sorry for wrong categorization. I somehow could not remove it via mobile…

I fixed the float(0) issue as well as added the “device_class” to power.

These are the entities when HEATING is working, Water has not worked that day
For explanation: Power sum sums up all power, and water/heating only get active when the respective service of the heatpump is online.

Now heating has worked and has stopped working - and sensors look like this after about 30 minutes:

Why do these sensors go back to “Unavailable” ?
Seems like the integration has problems with the zero-values.
Usually I would want them to show the last state that was valid
Here some screenshots of the data in grafana with "fill(null)