Product Attributes/Variations not showing on product page

For some reason, product attributes/variations will no longer show up on the product page for any of my products including newly added products. The select menus won’t load and the only thing visible is the “From $XXX” label. I’ve tried deactivating modules and reverting back to the default WP theme. But nothing is working so far and I’m starting to think it may have a few issues with WP 3.6 (was working fine under 3.5). One thing I’ve noticed is that the form does not contain the data for the product variations. Anyone experiencing or has experienced this before?

http://wordpress.org/plugins/woocommerce/