if the list doesn't show anything. it's mainly because you have all dlc installed and your game is up to date (based on updater)
it's normal.
if you game is not upto date or if you miss and dlc, you should have a pop up telling it, and then you choose wich dlc you want to instal (or update the game by checking "update")
honestly, if you use the updater. Then you are at the last possible update from it (wich is usually the last one availaable , and the dude keep it pretty updated wich is something i love aliots
)
technically you can't run the updater and end up with a game that miss an update. you can enven choose to instal only the update without the dlcs. so if there is no dlc to check, then it mean you have all of them.
normally (not sure) you can see it in your game itself, there should be all the dlcs icons. if one is half visible , theny ou miss it.
i never had troubles with the updater on my side :/ can't say for everybody.
ps: dang my english goes beserk XD