Yep, same here, with Surface Pro 3. But I also have a Lenovo Helix and on the Helix's Start8 menu, the "Sleep" selection is present just above "Hibernate" on Start8's expanded power button. Both devices are running 8.1 Pro fully updated and both with Start8 and ModernMix at their latest versions as of today.
I've also noticed in the Surface Pro 3's power settings "Choose what the power button does" and "Choose what closing the lid does" are the same exact settings - meaning it is not allowed to set the power button to shutdown and set close the lid to sleep for example. And the "Do Nothing" selection is just not present anywhere. In my experience with 20 some laptop/tablet devices, this is contrary all of those on which I've had the opportunity to view the power settings in both 8.1 and Windows 7 for that matter. Did I hear someone say, "Wait for Threshold"? I've tried all combinations in all the places in 8.1 where power settings can be changed and never does Start8 on the Surface Pro 3 show the "Sleep" selection in Start8 version 1.41 or 1.45. Start8 and ModernMix work flawlessly on 3 of the 4 devices in my home both computer and tablets.
In as much as I've gotten really attached to the pleasure of using the Surface Pro 3, it seems it's power option settings are of a new catagory, which may be confusing Start8 as they confused me.
