I'm having similar problems with Yoast WordPress SEO since I've updated to WordPress 3.5.
On any of my Posts or Pages I'm not able to use or see the area below the title "WordPress SEO by Yoast, which is where I normally add or revise "Focus Keyword", "SEO Title", or "Meta Description".
For those Posts or Pages where I've already added my SEO information I can see the SEO information on the summary listi all my Posts or Pages.
Also, within the the Settings section in Yoast WordPress SEO titled "Titles & Metas" there is no text below the tabs… General, Home, Post Types, Taxonomies, Other, Help. There should be many options to be filled in and when I click on a tab nothing happens.
Some other strange anomalies that may or may not be related to Yoast WordPress SEO but have occurred since I've updated to WordPress 3.5:
The tab in the upper right corner labeled "Screen Options" does not drop down when I click on it.
The fly-out menus that are part of the main WordPress menu on the left is not appearing. The only way I'm able to see pages below a major heading is to click on the button and then sub-category buttons appear.
Things I've tired:
Deactivated all plugins – That didn't change anything.
Reinstalled WordPress 3.5 – That didn't change anything.
Tried using Firefox instead of Safari – That didn't change anything.
Deactivated and Reactivated "WordPress SEO" – That didn't change anything.