Nothing new and not unique to Roamio:
It was fixed after a few days and I never knew what the problem was or whether complaining to Amazon actually made a difference. Several Amazon reps promised to email me when they found anything out -- but never did.
All I can suggest is complain to Amazon. Their Instant Video support number is: 877-442-1958.
I think Tivo's servers are also involved in some way when you order a Tivo download so can't rule out the possibility the fault is on Tivo's end. So I guess calling Tivo support might be in order.
If you get any immediate satisfaction from either support call, let us know.