No items in the basket

The plugin worked fine before, but recently there has been an issue.

The issue is following:

• The composite page looks correct with the products and prices. All changes and updates are visible.
• You can build a composite and the prices look correct.
• It will let you add the product in to the shopping basket but once in the basket it shows that the price is zero and there are no products in the composite.

Any advice what might cause this?

The page I need help with: [log in to see the link]