This has to be something new post-3/3. In the past, I have had multiple OZ award tickets issued by CO (SHARES) go off without a hitch, including one that was part of a complicated multi-airline itinerary that was reissued and resynced several times.
I suspect this is not a SHARES limitation, but rather a post-integration programming defect.
As a side note, enjoy OZ... great airline. All of my flights have been superb, nearly flawless (except for the fish out of FRA... don't do it
).