Resolved -
We discovered the cause of the issue and all services have been restored now.
Adding Store Products to the cart now functions correctly and buyers are able to complete the purchase using PayPal as the payment service provider.
We thank you for your understanding and patience.
Oct 28, 20:31 PDT
Investigating -
We are currently investigating an issue that is stopping the purchase of products from Format Stores being added to the Checkout for processing by PayPal.
We apologize for this issue and will provide further updates as they are known.
Oct 28, 17:11 PDT