It's the same with me. Mine is accounting for parts that I did on the first day compared to what I've actually done now.
As of 3:45 on 11/3 it's saying I've only completed 26% of Hard difficulty when in fact that is complete, so is medium and I'm about 75% done with Expert.
The best explanation, Activision wasn't prepared for the mass influx of users. It'll be worked out in time [I hope].