We had this problem before trying to purchase a UPS shipping label via Amazon Buy Shipping for an international order to Canada. Since we have to follow our next day shipping promise, we had to choose DHL that was twice the cost. However, the label for DHL printed right away.

We pursued the issue though, started a case and we exchanging info with Amazon CS for about a month. The resolution Amazon came up with sounded absurd. They said we were unable to purchase a label from UPS because the product title had some special characters like an "-", for example. This sounds ridiculous, as a seller has to make a product description in a special field that is part of the form for international shipping with Amazon Buy Shipping.

Now we are shipping a different product to the same customer in Canada, but are facing the same issue. We are literally forced to buy a more expensive shipping option from DHL. Why Buy Shipping works fine with them and doesn't work with UPS?

It would be ridiculous to change product titles not for SEO purposes, but for some stupid requirements of a courier service. I am sure they should have nothing to do with product titles. Product description in an international shipping form should be sufficient!