Stripe payment link not working - payment not possible

Hello,
first of all, I really appreciated latest updated that added the integration with the Stripe payment links. So thanks for the addition.

I'm trying to set it up and for the moment I'm using the Stripe sandbox environment to test the gateway, using the test card numbers that Stripe provides.
The payment works fine and the user is correctly redirected to the "thank you" page of Bookingpress.
However, the appointment booked is not actually generated (there is no new appointment in the staff member dashboard).
This can be seen also in the "thank you" page as the ID of the appointment is not generated, as the screenshot shows:

As you can see, in the yellow highlighted part, the user should see its appointment ID (in the image it's in italian, it translates literally into Booking ID:), but it's an empty field.

Thanks for the support, please consider this as urgent as it blocks completely any payment.