When I run zmgengraphs, it does populate all the graphs except what's under the "Anti-Spam/Anti-Virus Activity" tab. Not sure if it's failure to generate graphs based on amavisd data is a separate issue or related.
Edit: The bug I logged turned out to be a dupe of an already existing bug report #17977. Please use this link:
Bug 17977 - Server Status in admin console shows incorrect info.