Girtablulu after adding the workplace switcher did you reboot?
No. I didn't realize it was required. I'll give that a try on my dev machine tomorrow.
I just tried it on my Plasma 4.1 VM, and it's back to the problem I had a while ago: adding workspaces actually adds that many groups of identical workspaces (same contents in each). Rebooting doesn't clear that up.
EDIT: For example, if I change the settings to provide 6 workspaces, I get 6 groups of 6 workspaces. Removing one workspace from one group removes it from all 6 groups. I thought this was fixed, so it may be a regression.
I don't really need the Plasma VM for anything, other than experimenting with it, so if it works correctly on the dev machine tomorrow, I'll be a happy camper.