Disabling IPv6 and the Homegroup fix, both mentioned in this thread, did not work. PC will sleep automatically if power options are: display shutoff set to 1 min, and sleep PC set to 2 or 3 min OR if ethernet cable is unplugged from computer (with display/sleep set to 5/15 min).
Now, upon upgrading, PC will not sleep predictably when set to an idle interval of 30 min., even if 'powercfg /requests' shows 'none.' for every category. I had two 'powercfg /requestsoverrides' set via command line to ensure that this happened, however.
On windows 8, PC slept predictably when set to 30 min.
I recently upgraded my PC to windows 8.1 from a ~2 month old install of windows 8.