Doug,
I've actually had and solved this problem. Yahoo sent out a message several months ago that some people ignored. It stated that if you owned or moderated a group with an ID other than *@yahoo.com, many of your privileges would soon be disabled.
At that I was owning the group with "marks@..." which was a Yahoo service, but slightly different mail agent.? AT&T validates the login password, too.
Fearing future difficulties (but not anticipating the shutdown), I created a second ID, lvmarks2000@.... I subscribed it. Then with my original ID, I made the second ID also a moderator. Never touched the second ID for months. It was just insurance.
Then, when I needed to do a PG Offline download, the original ID wouldn't work. BUT THE SECOND ONE DID!
There is no reason to think that this same procedure won't work for you:
1) Create a real, native Yahoo ID
2) Give it Moderator privileges using your original ID
3) Give that ID to GIO and ask them to try again.
BTW, the founder of GIO seems to be an honorable person. If the group doesn't upload, I have every reason to believe that he will refund your money.
Larry
Laurence Marks