This is, in fact, consistent with the experience of the other user in the thread I linked you to earlier. Not that he said:
"At first I suspected the FeedBurner plugin was the culprit, but even with deactivating it, I still get empty feeds."
Fortunately, he goes on to say:
"Ok, after restoring my old DB and running the upgrade a second time it seemed to work...For some reason the old feed URL is still not working but a new feed URL turned up with the FB plugin deactivated."