Feature or bug - timed off

[pvoj]

Hi All,
I have my warm water heater powered from a special circuit. This circuit is switched on for 8 hours a day by the electric company (not is the same time and split to 2-3 periods).
I want to monitor the circuit by Domoticz. I have a mysensors node with a virtual relay powered from the same circuit the heater operated. If the power is on, I switch the relay on for a second. I send these pings to domoticz in every 2 minutes if the electricity is on. When it's off, no ping is sent.
I want to have a dummy switch in Domoticz which is on if pings are coming.
I have a blocky script to turn the dummy switch on for 3 minutes (when the ping arrives). Logically, during the 3 minutes if I switch it for another 3 minutes, the automatic off command would be postponed for another 3 minutes. But it is not working this way. The dummy switch turns off even it got a command 1 minute ago to turn on for 3 minutes.
Is it a feature or a bug in Blocky?
Any suggestions to make it work?
Thanks!