This may happen due to the discount code associated with the product being blank. The solution is to add a discount code.
  1. Navigate to Fundraising > select eCommerce
  2. Select the Stores tab
  3. Find your Store and click Edit
  4. Navigate to step 10. Discounts
  5. Notate all of the discount codes under "Your Selections"
  6. Select the Discounts tab from the top menu
  7. Edit each discount code and navigate to step 4. Eligibility
  8. Populate option 1. Enter a discount code