What could be the problem of a customer to not be able to see all his tickets in the portal?

When he opens the ticket with a link, he can view the specific ticket, but on the section with tickets he is not able to see all his tickets, and it says that he doesnt have any tickets?

Which is strange, somehow the tickets are not connected to his profile maybe, but he is the requester so I dont think that is the case.

What could be the reason?