Usually it's because of a backlog in the visa office (which doesn't seem to be the case here) or if the applicant is already in Canada. You could try writing a case specific inquiry, but it's anyone's guess whether you will get an answer.
My partner is from Japan and we were pretty sure his application would be sent to Manila (they closed the VO in Tokyo) but they also sent his to Ottawa. Not sure why :/
Hopefully our applications are still processed as quick as possible! :>