What is hanging up on my computer is Hibernate, which the default Power Management Balanced settings | Advanced Settings has occurring after 180 minutes, or 3 hours, of inactivity ( Sleep triggers off after 30 minutes of inactivity ).
It was my error to think that Sleep was not working for my computer on Windows 8.1.
I realized just recently that Sleep is working on my computer, even if I change nothing in the default Power Management Balanced settings which I use and also accept the defaults in the Device Manager for my USB devices and USB hubs. Hibernate not working but Sleep is working
