I have the same issue as MagicJello. I did just get my Asus Transformer T100 with windows 8.1 and just discovered this problem. It is most obvious when listening to music for example by using Spotify. When doing so I do not want it to go to sleep mode but of course it is ok for the screen to be turned off to save battery.
So I set that the computer should never go to sleep. I can then go to advanced settings and change after how long I want the display to be turned off. But when I do so, and close the power settings window, and then open the settings again I can see that the option to never go to sleep mode has been changed to the same value as I set the time for the display to be turned off.
There seem to be some sort of bug. Can it be fixed?
In windows 7 there were under power options different options for when the display should be dimmed, when it should be turned off and when the computer should go to sleep mode. I can not understand why these options have been reduced to only the option to go to sleep mode.