I have a fresh install of Ubuntu 12.04 on my Dell Studio XPS (Specs at end of post) with nvidia-current installed as the proprietary drivers and I'm mainly using Gnome Classic but this issue does happen in Unity too.
According to the workspace switcher in the corner, I have 4 workspaces in a 2x2 format, when I click on another workspace it only switches between 2. Selecting workspace 3 on the launcher switches to 1 and 4 switches to 2. I have the compiz cube enabled and when rotating workspaces it is just a plane with a dekstop on each face rather than the cube.
If I go into the compiz settings and have a look at the number of workspaces, it only shows 1 and if I increase them to 4 the workspace switcher changes to a 4x1 arrangement and selecting any of the other 3 not just changes to that workspace but without a desktop environment or any windows (including conky). If it hit CTRL+ALT+T for terminal, it then jumps back to workspace 1 and opens a terminal.
I have been using my laptop with another monitor configured in twinview, but I have also tried disabling this and using one monitor and the issue still occurs.
In want to configure it to have 4 workspaces which display properly in the compiz cube and it would be nice to have this working across both monitors.
[It would be wonderful to have 4 workspaces for each monitor and a separate cube and switcher for each one giving 8 total but I think that's just greedy :p]
Laptop spec
i7-2630QM
12GB RAM
NVIDIA gefore 555M (3D display so optimus is disabled ignores the intel HD3000)
17" Screen 1920x1080
Second monitor acer p223w 1680x1050