Hello, The Featured Image does not work for me in IE, Firefox, or Chrome. I'm uncertain this issue is related to the same causes as referenced in the post forum titled, "Add Media and Featured Image buttons not working", posted by daverage, so please accept my apologies if this would be considered a duplicate ticket. I'm simply unsure whether to open a new ticket or not at this point.
This is a new install of WordPress 3.5RC3, multisite.
In all of the cases, the featured image will upload into a gallery. In none of the cases will the featured image show up in the featured image meta box, nor in the body of a post or page. Even this is a change from RC2, where in some cases I would at least see the featured image in the metabox.
This was tested before activating any child themes or plugins.
Again, tremendous thanks to the awesome WordPress team for all you do!