Cart not saving in Opera

I’ve just upgraded wp-ecommerce and related plugins and everything works fine except for when I view the site with Opera. Not a biggie – accounts for 0.32% of site traffic but nonetheless, sales are sales.

Opera has cookies enabled.

If I add something to the cart it shows in the sidebar. If I add another book, move to another page, or try to checkout the cart is lost.

There are no errors in the console or errors tab.

Any ideas on how to fix?

https://wordpress.org/plugins/wp-e-commerce/