If you type /dopuslocaldata\State Data into the location field in Opus it should take you to a settings directory.
Open that same directory in Explorer, arrange some Opus windows in a way you'll recognise, then exit Opus via the tray icon.
In the Explorer window you should see that openlisters.oll gets updated. You can open it in a text editor to confirm that it saved the right sort of thing (look for the directory paths you had open as a good indicator).
If that part is working but restarting Opus gets you something else then we can look at that next...