I had a problem like this, it turned out to be a utility I used called Win10OldNewExplorer because the preview pane was moved in Win 10 and I like the Win 7 preview pane at the bottom, and this tool fixes it.
I had to stop using it as it made Adrenalin crash. So it's probably something that you have installed. It can be difficult to find out what is causing it, in my case I uninstalled various tools until finally I nailed it down. I would really think it's some software or utility like in my case causing it. I hope you find a solution.