Add to cart stops working
I'm using Kickstart 2, products have a single attribute "card type" and I'm also using commerce registration.
The site is for conference registration and everything has been gong really well until I noticed while testing that clicking "add to cart" doesn't add the item to the cart. The page reloads, as if it was about to display the added to cart floating layer but doesn't do anything. When checking /cart it's empty.
I've found that creating a new product variation and display fix the problem, but something is causing the issue to reoccur. Firstly I thought it was to do with making a small change to a displays fields but now I'm not so sure.
Has anyone else had an issue like this?
Thanks for your help.