If you find in page source, you'll find that your gridview is rendered properly. Make sure that you are not hiding it somewhere with accordian style. Just take a review and try to find the exact place.
Anyway, you can make it visible in your jquery snippet(Not a good practice, find the root cause first). Try this
$("#accordion > li > div").click(function () {
if (false == $(this).next().is(':visible')) {
$('#accordion ul').slideUp(300);
}
$(this).next().slideToggle(300);
});
Hope it helps.
--Amit