Right now, all international shipping is a problem!!!
Most people don't think about the fact that our international mail is usually sent overseas on passenger planes. Now, with nearly 90% of international flights canceled, there are far fewer planes. Delivery times can run up to six weeks for major countries in Europe. And once the package has left the USA, tracking is terrible (this is not new, but used to be a week or so and the customer would have it--now there is no telling how long it will be "lost" before it is delivered.)
UPS and FedEx are much more expensive, but may be worth it if the customer does not want to be patient.
Good Luck whatever you try!!
ed