Hello again,
Please provide with your Ftp access these elements :
- A backend access (with the full access)
- A step by step process, and everything required to complete the order, elements like sandbox customer reference AND Test Credit Card, the point is to reproduce exactly your Paypal express test, and see precisely, what you see.
This will allow us to solve directly on your website your issue, precise as well if your website is production phase.
Awaiting your returns to progress on your subject.
Regards