Dear sister,
I have helped a lot of people with their GCMS notes and I found this; when CIC is busy doing background check SECURITY Assessment always say NOT STARTED. But why don't they write IN PROGRESS for Security like they do with Medical or Eligibility? Because SEC/CRIM are very sensitive jobs and need to be done in total secrecy since they involve different countries. Unlike Medical Assessment which is also a part of background check, Medical or Eligibility are completely under Canadian control and therefore Canada doesn't mind showing all the stages of these 2 assessments that I just mentioned a while ago (Medical and Eligibility).
So, if you see Security with a BLANK STATUS and SUBSCRIPTION 15.(1) rest assured that it's ALREADY DONE and completed. However, CIC agents will never tell you the whole truth of your file. You got to learn how to get that truth by listening to your brothers and sisters who have walked that road before. Your visa office wants to surprise you that is the bottom line. So be patient and stay positive for everything will one day come to an end.
Thank you