Alright, I had the dlc-no-worky problem and, as with any problem I encounter, it made me research like crazy. Mine's fixed, and it's one of those that wouldn't go away with the most common fixes (which, btw, I'm posting right here... make sure you read through the following link before attempting my fix. Odds are you don't have to go through the trouble I did.)
linky!
Here's the skinny on this problem, at least as far as I can tell.
-DA:O is patched to v1.5; that is the most current version
-sometime in the recent past Origin started being more picky about applying patches, the Origin downloader automatically updates DA:O to v1.5
-The Origin version of the patch, for whatever reason (I can't think of one right off the top of my head) sometimes (always in my case) removes the program "DAUpdaterSVC." Just flat-out deletes it. No replacement, and it gets rid of a bunch of other things too.
Problem is, without the DAUpdaterSVC program, your dlc doesn't work. In fact, the screen in-game where you download dlc is bugged. And there's no real discernable way to fix it.
Here's my fix:
-Download the v1.5 update from Bioware (it's correct, and the Bioware version of the update doesn't delete a bunch of **bleep** from your game.
-Install the externally-downloaded update.
Now, don't panic. Your Origin game will not start up like this. Origin won't recognize the v1.5 update from Bioware, and the game will flash a message telling you that it has to be reinstalled. Don't worry, that's normall and can be fixed.
-Now go into your game files (programx(86)/origin games/Dragon Age/bin_ship) and locate DAUpdaterSvc.Service.
-Copy this application and paste it elsewhere on your hard drive, outside of the Origin folder.
-Open Origin, locate Dragon Age in your "my games" section.
-Right click on it. Click "check for updates"
Origin will once again "update" the game, removing anything remotely useful in helping you get dlc, and removing the real v1.5 update. Now you'll be able to play it, but still have your dlc problem.
-Go back into your game files, back to the bin_ship folder, and paste in the DAUpdaterSvc.Service program.
Now, depending on how much Origin has screwed up your game, there might be one additional step to fixing this problem, and that's to turn on the service from either services.msc or from command prompt. Those fixes can be found at the link in the first part of this post.
This fix should get the updater service working again (Windows will actually be able to find it because it won't have been deleted). Now, for me, the dlc page is still bugged, but when I load the game and then sign into the bioware servers from the in-game window, and then look at my dlc page the "download progress" tab (which I still can't get to--I'm guessing those are some of the other files Origin deleted from the game, but I'm not sure which ones) has a red exclamation mark on it. And my dlc starts to show up after I leave DA:O open for some time like this.
Also, this content isn't being downloaded through Origin. That's probably the reason Origin destroyed the game's normal updater anyway, so that every little bit of dlc would have to be registered and purchased through Origin. Unfortunately in my case it seems to have "forgotten" what "Ultimate edition" means. This fix makes the game act like it used to and install all of the content that comes with the ultimate edition. I can't guarantee it will work indefinitely, because Bioware might very well transition their record keeping to Origin and then we'll have to re-purchase all dlc again. Use it or lose it, you know?