Programs from All Workspaces Show on Same (Classic) Taskbar After 12.04 Upgrade

[OzzyFrank]

OK, this is a new one: when I switch workspaces, the taskbar (I'm obviously using Gnome 3 Classic) is the same in each, meaning even if I have nothing open in Workspace 2, the taskbar will be full of apps open in Workspace 1, and clicking any will see me back at Workspace 1. Similarly, any apps I have open in Workspace 2 will be visible in the taskbar in Workspace 1, and clicking one will take me to Workspace 2.

Now, I know right-clicking a taskbar button can give you the option of "Only on This Workspace", but besides the fact I don't really want to do this for every thing I ever open (especially since I never had to before the upgrade), but it simply doesn't work, so isn't even an option.

I've had to fiddle with some Compiz settings after the upgrade - like disabling Unity within the Classic desktop so both weren't running at once, and enabling "Place Windows" so everything wasn't opening in the top-left with the titlebars hidden under the top panel - but I simply can't find where to change this really annoying setting which renders the whole concept of workspaces useless. Any ideas?

PS: The obvious solution of opening "Window List Preferences" and disabling "Show windows from all workspaces" is a no-go, as it is already set to "Show windows from current workspace", which is the default.