I'm having the same problem when trying to deliver Kitely Market items to my avatar on Craft World.
The message I get is always the same:
Avatar not found: "Camie Rembrandt" at Craft World.
Check that the avatar name is correct and try again.
I've tried doing everything you suggested on this thread.
I've even tried purchasing the item while in-world on Craft World and on Kitely at the same time using two different viewers.
Unfortunately nothing worked.