Looks like all inserters are capable of lseeping correctly when they are powered, but not all inserters sleeps when power is cut. The number of inserters sleeping is actually decreasing when the power is cut. Only tested this with fast inserters but the problem might also occur with other kind of inserters.
None of the machines in this picture has power

Steps to Reporduce:
- Remove the big electric pole the player is standing next to in the map below to cut the power to the lower half of my base.
- Going straight down and around the oil processing will lead to a furnace area where the problem is very visible.
https://www.dropbox.com/s/k1c80keegmrsd ... g.zip?dl=0