Problem: I have a stationary computer with ubuntu linux 18.04. 3 monitors connected and I can have maximum 9 workspaces. Even if I set "Gnome tweak tool" to 12 workspaces it shows only 9 workspaces. Note! The left/right monitor shows 12 workspaces.
Wanted behaviour: To set workspaces to more then 9 monitors, and that both center screen and side monitors show icon for the amount of screens.
(The packages are required but does not solve the problem with limit maximum 9 workspaces)
Gnome tweaks tool - To have extra workspaces.
Gnoe workspace grid -
Multi monitor add-on - to have workspaces visible on left/right screens.