Shelly 1PM power consumption accuracy

I've found strange behaviour of power consumption calculation.

Shelly 1PM shows the pretty accurate value of the current power consumption of my LED lamp (~60W).

When I turn on the shelly relay correct current power appears in about 3 seconds.

When I turn off the shelly relay correct current power zeroed instantly.

So long all good.

But when it comes to total energy consumption Shelly shows the same 60 Watt*minute for the case when the lamp was turned on full minute and for case when the lamp was turned on for a few seconds. curl -s http://192.168.1.105/status | jq .meters[0]:

{
  "power": 0,
  "overpower": 0,
  "is_valid": true,
  "timestamp": 1637675653,
  "counters": [
    60.682,
    60.006,
    0
  ],
  "total": 223
}

It seems there is some (software) problem in power consumption calculation.

Maybe the current power did not reset after the load turned off as there are no more pulse signals from BL0937 energy meter IC?

FW version: 20211109-130756/v1.11.7-g682a0db

I've mounted Shelly 2.5 right before 1PM and turned on 60W lamp for about 10 sec.

Shelly 2.5 shows the expected 10 Watt*minute, but Shelly 1PM shows 52 Watt*minute.

As instantaneous power is correct I suppose this 1PM inaccuracy is rather a software bug than a hardware limitation.

$ curl -s http://192.168.1.175/status http://192.168.1.105/status | jq -c .meters[0]

{"power":0,"overpower":0,"is_valid":true,"timestamp":1637698442,"counters":[0,9.556,0],"total":10}

{"power":0,"overpower":0,"is_valid":true,"timestamp":1637698442,"counters":[0,52.359,0],"total":52}

Shelly 2.5 FW "20211109-125214/v1.11.7-g682a0db"

Shelly 1PM FW "20211109-130756/v1.11.7-g682a0db"

It appears that Shelly power meter is inaccurate only when the load is turned on/off by the same Shelly device (1PM or 2.5).

I've performed yet another test with the third actor: Shelly 1.

The wiring is: power outlet -> shelly 2.5 -> shelly 1PM -> shelly 1 -> 70 W halogen lamp. Shellies connected one after another so the lamp lit up only when all shellies turned on.

Test case 1, turn on the lamp by Shelly1 for ~10 seconds: power consumption measured by shelly 2.5: 10 Watt*minute, shelly 1PM: 16 Watt*minute (let assume it as pretty accurate).

Test case 2, turn on the lamp by Shelly 1PM for ~10 seconds: power consumption measured by shelly 2.5: 11 Watt*minute, shelly 1PM: 66 Watt*minute.

Test case 3, turn on the lamp by Shelly 2.5 for ~10 seconds: power consumption measured by shelly 2.5: 48 Watt*minute.