So I noticed this with the release version of MC11 and I've upgraded to the latest version and still have the problem.
When I go to playing now and a song is playing, if I right-click on the Visualization screen menu bar, I used to be able to see all my choices for visualization (Cover Art, 3D Visualization, G-Force, etc.). But now I don't get any visualizations. Sometimes I get 3 choices -- QuickTime (don't know what that even does), Cover Art, and Track Info.
When I check my plug-ins settings, I have 3D Visualization and Visualizations installed, but they are not showing up. And even though I just downloaded and installed the latest version of G-Force, that's not showing up either.
The strange this is that on one my Track Info choices (Push's Aruba II? I think), it has a small screen that plays the visualization and it works there -- there is actually a visulazition playing. And I can right-click on that little screen and choose options (random, cycle, etc.)
Has anyone else had this problem? Does anyone know how to fix it?