In trying to identify mystery devices, including one that I think is spurious, a “power meter” display for “other” would be very useful.
For example if, except for perhaps some noise, “other” consistently changed out of phase with the device we’re investigating, so that the total of “other” and the mystery was unchanged (with all other loads in other not changing), or if the opposite happened, we’d be able to continue sleuthing in different directions.