Check this ticket: http://core.trac.wordpress.org/ticket/17590
Quickfix by husobj:
function my_page_css_class( $css_class, $page ) {
global $post;
if ( $post->ID == $page->ID ) {
$css_class[] = 'current_page_item';
}
return $css_class;
}
add_filter( 'page_css_class', 'my_page_css_class', 10, 2 );
The quickfix might be an easier alternative?
Cheers