I just had this problem. The destination address field was too long. Before hitting the Pay and Print button, click on the Change button for the destination address. You might see something like this:
What Ebay shows as the destination address:
XXX
Building name, 12345678 Long_long_street_name, Apt 322
XXX, XXX XXXXX
When you click on the "Change" button, you see this for the first address box:
Building name, 12345678 Long_long_street_name,
Note that the apartment does not show up on the second address line but is past the end of the first box. You need to move the apartment (or whatever is causing the overflow) from the first line to the second address line. It is vital to remove the extra characters from the first box since that is what is causing the problem. The address boxes should look like this:
Building name, 12345678 Long_long_street_name
Apt 322
After doing this, everything worked normally.