Thanks @dougaitken for your answer.
Two cases have in common that they are from Germany, so I configured my VPN from Germany.
They both were trying to buy using credit card and they both want to save the card data for the future.
And all the shipping adresses are in Germany and Sweden.
We have another case from Sweden.
Hope it helps and that you can reproduce it. Please, let me know.
Yesterday we have a client in Irland that could pay without any problem.
Thanks again for your support. Hoping to hear from you soon.