I noticed that I can access to Customize if I am on the page that have https. But not when http or in admin.
I am having this same problem. I installed WordPress v3.5.1 and no matter which theme I select, the customize theme page (or theme options page) only shows the left column menu, but none of the menu choices will toggle to reveal the options; and there is nothing but blank white space in the middle of the screen.
Given that this is happening for ALL the themes, including twenty-twelve, it appears that the problem is not specific to a particular theme.
BTW, the actual theme I am trying to customize is Magazine Basic by c.bavota. The Theme Options (customize) page does not function properly as described above.
Anything you can share is appreciated.
@bizcoach_blogger – please start your own thread – this one is not relevant – it’s for a plugin.
You can start a new post for your theme: http://wordpress.org/support/theme/magazine-basic#postform
Please also include a link to your site.