UPDATE: I have the problem fixed. I don’t know which trick worked, but re-installing Windows 8.1 itself, and then drivers, EyeX engine, and a lot of uninstall-restart-reinstall cycles, finally solved the problem.
@maverick85 if you still have problems, try uninstalling all Tobii stuff, restart, uninstall USB drivers through Device Manager, restart, install USB 3.0 drivers, then Tobii stuff and again restart! 😀