Plugin Manager won't appear

My client just purchased a full copy of WaveLab Pro 11 for me, for software development purposes. I just tried creating an empty project, then opening File->Preferences->Plug-ins…but nothing happens? No plugin manager dialog, no nothing.

Help?

I contacted support chat and was directed to follow the instructions for resetting plugin preferences, here:

You should see a window like this:

Just in case, try menu
Workspace > Layout > Default