Yes, Not applicable->your application is in progress(I'm a bit fuzzy about the exact words)...->we are processing your background check...(I think it changed with MEP or a few days after), missed the NA in between though.
On tracker if I use the inspect page trick, I can see that in the history list, the new entry has key "security", so I'm assuming that my security has started. I thought if most people don't see this type of update, they might be part of the "low risk" population, and that might mean I'd be going through more comprehensive security check. If that's the case, it might be pretty annoying. Can't plan my life around 1~18 months of processing time