I have an SP3 with a SP4 type cover. I cannot get it to stay in hibernate. Occasionally it seems to stay, but that is at best one out of fives times and usually be first time after I have just adjusted settings. Normally when I close the cover it wakes right back up. I have messed with all related settings including turning off the cover from doing any action, though I don't see any options for action on open of cover. It is using current normal updates. I do not have a SP3 cover to test with to see if that performs any differently. Doesn't appear to be any difference on battery or plugged in. The only thing that does seem to work is if I make the lid close action to hibernate it seems to stay in hibernate, but that is extremely inconvenient to wait for wake.