maybe they did that based on the countries from which the applicants came from, for example, they may know by their experiences that people from England may be easier to get their NC finally cleared? You may have known that people from England got much more eb gc than people from mainland china.
I am afraid it may be not true that they need a lot of time to put the NC results into CIS system, because everyone has been marked an A#, when the results come back from FBI, the system should be very easy to complete that.
"did not be completed" should be at the FBI side.