Trying a reinstall of the desktop can't hurt. You might use the standard uninstall routine in Windows (if on Windows) first and then install fresh from
www.kobosetup.com. Depending on your Internet connection and computer, it shouldn't take too long. At least then you can scratch that off as part of the problem.
I never log out of Kobo Desktop but, then, I also rarely use it so it isn't running on my computer except for one off uses.