Yoast SEO v1.4.12
Wordpress v3.5.2
I uninstalled every plugin and changed themes.
On my Pages list view, the SEO column shows different colored dots but hover-over shows "NA" for all of them. The same on individual pages - the colored dot on hover-over does not show a tooltip "good, bad, great, etc."
I just updated from Yoast SEO v1.3.4.4 where everything appeared as expected.