I have a 'fresh install' of WP 3.4.2, no extra plugins yet.
The GamePress theme functions to add TABS or an ACCORDION don't work when added to posts or as a sidebar widget.
But, strangely enough they do work when I go to 'Appearance' -> 'Themes' -> 'Customise'.
You can verify here: http://mista.mine.nu/game-review/new-test/#
Anyone have an idea on where I could look?