If Sydney were to process them completely, that would be a brand new thing -- up to now they have always transferred them to Mississauga or to a local VO. Not saying it's impossible, but it definitely has not been an option in the past so it would have to be a very new change.
I can only speculate on why files are still lying in Sydney -- for some people, it's clearly because their VO is so backlogged it takes forever to forward it (all the people going through Mexico VO are in this situation). More recently we've seen it with some Indian applicants, and I have no clue why this is -- in that case it could be something as simple as, say, one out of every five applications is held to send to New Delhi or it could be something as complicated as there being some delay with getting a response on a background check. Mississauga has also been sent so many applications in recent months I wouldn't be surprised if they're starting to get more backed up too.
Whatever it is, I can only imagine how frustrating being in that position would be. At least the Mexico VO applicants know WHY, but for everyone else it seems to be a mystery for now.