Sometimes it adds to cart, sometimes it does not.

I using formidable pro + woocommerce add on and have created a form to use on a woocommerce product page. Sometimes when clicking on "add to cart" the product successfully is added to the cart, but most times I land on the cart page with "your cart is currently empty". A few times it even said "form submitted successfully" but stayed on the product page and the form was gone. WordPress and all plugins are current.

Here is a link to the product page: http://myhealthbusiness.com.au/product/custom-branded-health-challenge/

NOTE the page is still in development, so you can't actually checkout because I have not set up a payment gateway yet.

I have searched both forums and can't find any similar problems.

Thanks in advance for any help on this!