Hi,
i think it’s due to the way the standard chart item works.
It tries to scale the values somewhat reasonable. If your values are just 0 and 1, the result is what you see. For example, here’s how my chart for motion sensor would look:
To overcome this, I’m afraid you either have to use a more sophisticated chart engine (check this post: InfluxDB+Grafana persistence and graphing) or in the case of 0 1 values display the Open/Close times instead.
HTH,
Regards,
-OLI