Workspaces dont work here correctly on a 4 monitor setup with a matrox multi-display card. The monitors work with a non HD screen resulution.
So Fabio might be right and the behaviour might depend on certain factors. THe deeper lying cause might be in the way cubase does window handling (including the menu bar window…). I suspect this because when I move the menu bar to a separate 5th display and open all other windows on the other 4 screens the workspaces work correctly…
Cubase btw. is the only application here that does not handle the multi-screen thing correctly.
Please do not neglect non-HD and non-4K screens.