What Lansweeper is reporting is likely correct. Recent Windows operating systems (Windows 8, Windows 10...) will by default not fully shut down the computer, even if you choose the shutdown option in the OS. They'll partially hibernate instead. This is part of a new "fast startup" feature in Windows. We've discussed this in another forum topic as well,
here. Disabling fast startup on your Windows 8.1 computers will likely resolve your issue and make the computers fully shut down. More info on enabling/disabling fast startup can be found
here.