I am having the same problem. Preview in Editor is already turned off and the preset has been saved. This has been annoying me for weeks. Is there another Preview setting somewhere that also needs to be disabled?? I am also using V13. Windows 10.
This problem still exists...I am using Snagit 2019 on a Mac, am having this issue now, and have had this issue for several prior versions of Snagit Mac. I also use Snagit on a number of Windows 10 PCs and the setting works as advertised there.