Paypal payment problem with Cloudflare

I have a problem with Cloudflare:
When a customer buys something from me, I get the money but the customer does not get his product, because there seems to be some kind of transmission problem between CLoudflare and my software (WemX). The funny thing is that it works with a new domain of mine without any problem.
It cannot be due to paypal and not6 to the programme…

Hello there, sorry to read that you are experiencing difficulties.

For clarity, what do you mean by customer does not get the product?

Are you facing any errors? If so, could you share more details about that?

Also, what is the domain in question and what makes you discern this issue is caused by Cloudflare?