Windows 8.1 Pro laptop won't sleep after unattended WSE2012 backup session

Hello,

I have a new Windows 8.1 Laptop, a Puget Computer V560i laptop using a Clevo W350STQ motherboard.  The laptop is part of a Windows Server Essentials 2012 domain.  I have the latest BIOS and drivers installed, including graphics drivers.  Windows 8.1 Pro was installed native (not an upgrade).

The WSE2012 server wakes the sleeping laptop every night between 4 and 5 AM to perform a client backup.  This works fine.  The problem is that the laptop does not go back to sleep.

The laptop is normally connected to power and sleeps every night---so the server can wake it up.  The laptop is set to go to sleep in 30 minutes via Control Panel | Power Options | Balanced | Plugged In.

If I test the laptop during a normal session and don't interact with it, the laptop goes to sleep in 30 minutes fine.  Asking the laptop to sleep manually also always works fine.

Note that other client machines on the domain go back to sleep after backup.

I exposed the "System unattended sleep timeout" setting by updating the registry.  This timer is set to 2 minutes for ac and dc, the default (as expected).

After a WSE2012 backup via WOL, the laptop does not go back to sleep.  I can always manually put the laptop to sleep.  This morning, at 9 AM I tried various things:

1. From cmd (admin), tried powercfg -requests to see if anything was blocking sleep. Nothing was blocking.  I expected this given I can manually put the laptop to sleep.
2. Examined the event log to see if any events indicated blocked sleep.  No events present.
3. Tried to see if the system would go back to sleep on it's own after manual user intervention.  It would not sleep this way.
4. Manually slept the system, woke it, and then tried to see if the system would go back to sleep on it's own.  It would not.
5. Rebooted the system and then tried to see if the system would go back to sleep on it's own.  It slept this time.

So, my working theory is that a WOL session somehow blocks unattended sleep until the next reboot.

For a while, if the laptop had not gone to sleep on it's own since the last reboot, it would sleep after the server backup.  If the laptop had gone to sleep at least once on it's own since the last reboot, it would not sleep after server backup.  This behavior has changed---the laptop now never goes back to sleep after server backup.  It will go to sleep on it's own during a normal user session.

Does anyone have any ideas on how to get the laptop to go back to sleep after an unattended server backup session?

Thanks.