Hello There,
Sorry to hear that you’ve encountered this issue.
We tested the card decline flow using a test card on our end, and the order is correctly marked as Failed. You may check the screenshot here:
https://www.awesomescreenshot.com/image/57515686?key=ba486654ad19708f3cca10fc04daf0a8.
However, since you are facing a different behavior on your end, we kindly request you to share staging site access along with temporary FTP access, as mentioned in the other thread. This will help us investigate both issues thoroughly and assist you accordingly.
While sharing the access don’t forget to mark your reply as private.
We look forward to hearing back from you.