My situation is similar.
AOR Feb 2020. I also had an ADR in December last year, and submitted the requested docs on Dec 13. Probably this timing was quite unlucky, because it was right before the holiday season.
And by the time when IRCC folks got back from the holidays around January 6-7, my application again ended up in the middle of the stack.
I finally managed to reach the IRCC call center today, and they confirmed that the Security check hasn't been started yet because "every application is different and bla bla bla"