There are many applications under 400 at assessment stage as well.It seems that for now they are just changing the status of the applications for applicants with CRS > 400. Correct me if anyone with CRS < 400 and application submitted in November has seen his/her status moved from Submitted.
There isn't any pattern for who's getting picked from the queue or not.
It's just random. We can't do much for now but be patient.