The thread is old but the issue is still prevalent - it appeared quite recently on my Surface Book.
After checking whether the power button press is actually set to put the machine to sleep in the Power Options of Control Panel, and making sure that Hyper-V is indeed disabled, whenever I press the power button, it still shows the 'Slide to shut down your PC' prompt.
I searched for other solutions and found only one, which suggested 2-button shutdown
. Not surprisingly, it did not work. Has any of you had more luck in fixing this problem?
*EDIT* I tried shutting down by holding the power button for a few seconds and then turning back on. While turning back on, Windows communicated reconfiguring some features. It solved the issue for me.