Drupal commerce cart not working after commerce_discount is changed when upgrading from kickstart-7.x-2.12 to 7.x-2.13

When I upgrade my site from kickstart 2.12 to 2.13 I am no longer able to add items to the shopping cart. The Item added successfully dialogue box shows, but nothing is actually added to the cart.

When I ran update.php is lists the modules that need to be updated. If I replace the commerce_discount (profiles/commerce_kickstart/modules/contrib/commerce_discount) module with the version from 2.12 the issue is no longer triggered.

Ideally I would like to update to the newest version of kickstart, but the not able to add to cart problem also gets triggered when I tried to update to newer versions.

I tried updating to the alpha version of the module from https://www.drupal.org/project/commerce_discount but this did not fix the issue.

I can also trigger this issue on a version of my site, on kickstart 2.12, by disabling Commerce Discount module in the modules list.

Can anyone suggest what is causing this problem and how to fix it?