Had the same problem. If you reload the page when you get the "There are no characters available for World Transfer.", there is a chance it will load correctly. I've been able to get all the way to the final confirmation doing this. However, some of the Destination Worlds listed are the over-crowded ones... and some of the uncrowded ones aren't listed. So there is something else going on with their setup of the service. Anyway, hit refresh and confirm form resubmission yadda yadda and it may work for you as well.