One hint: If you unplug in the middle of something running (your unknown showing up as a bubble) and the bubble doesn’t go away, that doesn’t necessarily mean that that isn’t the device. Sometimes the device switching off looks different from unplugging to Sense, so the bubble will persist. The only place that you can see exact realtime feedback is in the Power Meter. But there it might be difficult to separate drop in power between refrigerator usage ice maker usage. One option is to leave the refrigerator unplugged for a while and see if the 3min spikes come back. If they stop, then it’s likely the icemaker.
Here’s good video on how to trace what the device really is:
