"Unable to Authorize the listed DLC"

Oddly enough I seem to be running into this same issue. The last time I played mass effect was roughly one year ago. (without any issues)

The only thing that's changed since then has been my computer name. So that would lead me to believe that origin dlc somehow saves to your computer name. I would recommend uninstalling then reinstalling the game but unfortunately I don't think that's going to work.

Please log into the alliance network with the account used to purchase the DLC.
                  Collectors edition online Pass entitlement
                  From ashes
                  Citadel base package
                  Citadel
                  Omega
                  Leviathan
                  Mass effect three extended cut
                  Dark horse comic
                  Alternate appearance pack one G(arrus, Liara, EDI)

Adding Screen Cap: http://i.imgur.com/ZJ2mWqc.jpg 

Any assistance from would be much appreciated.

I just did that unfortunately, I did uninstall and reinstall, to no avail...I can't even speak to anyone over the phone, did they get rid of their live chat feature? 

I reverted back to my old computer name but I'm still not finding any resolution on this issue.

Disabled Windows firewall
Made sure there were no other updates for mass effect
Disabled all virus software
Ran a repair on the game

After making the changes above I still do not have any resolution.

At this point I'm at a loss... Not sure what else to try hopefully someone from EA will respond soon.

I just noticed something interesting. So I disabled not only the Origin Cloud Syncing ability, but deleted my save game profile etc from 'My Documents' It deleted all my settings and game files, and the same message appeared when running the game again, but interestingly, it now added the 'Collectors Edition' and 'From Ashes' to the list, where it wasn't there before.

I have a feeling that it's possible that, that career was made before EA added patches that there was no issue and it worked just fine but since being patched that this issue arose.  

Another interesting discovery was that when moving the DLC folders for the game located in Program Files/Origin Games/Mass Effect 3/BIOGame/DLC folder, it wont appear on the 'Unable to Authorize....' message, I'm certain it removes the content as if it isn't there however it tells me that there is a problem with origin or the game relating to those files...

So I went ahead & did another uninstall/install for ME3 since I reverted my computer name. Still running into the same error. . . . 

Also I was testing to see if I would get the same message in ME2. After launching ME2 it  failed to connect online but since ME2 has the option to login

to my account from ingame it worked & I had all DLC access in ME2. ((However my saved games were gone))

Also made the following changes again.

1.) Disabled Windows Firewall

2.) Disabled all 3rd party applications. (Skype, Steam, Facebook App, Ect)

3.) Disabled Virus Protection. (Uninstalled them as a last resort)

4.) Checked for Updates for ME3. (No Resolution)

5.) Ran Repair on ME3. (No Resolution)

6.) Uninstalled / Reinstalled ME3. (No Resolution)

Do I just uninstall Origin all together with every game & install it on another Drive?? But even if I do that I should still receive the following message.
""Please log in to the Alliance Network with the account used to purchase the DLC""

I still think that the computer name has something to do with this issue.

Example: 

1.) Log into your computer under the Username: James (James has all DLC & Collectors Edition)

2.) Log into your computer under the Username: Shepard (Shepard has Omega DLC)

When launching the game I could see both users running into ""Please log in to the Alliance Network with the account used to purchase the DLC""

The only reason I come to this conclusion is because I changed my computer name thus creating a new Users Folder in ""C:\Users"" where my 

saved game files can be accessed. Which would make sense since I was no longer able to find any Saved files from when I played ME2/ME3 back in the day.

And yes I reverted my computer name back to what original was when I first installed ME3 & it still will not allow me to access the DLC. 

So do I create a new account on my computer?? Install Origin/ME3 & hope it will work? 

Any input at this point would be awesome & very much appreciated. 

Any luck yet Cyrisal?

FYI

I just uninstalled ME3/Origin (again) now I'm going to create a second account on my computer. 

Then reinstall everything on my second windows account. I will keep you posted if this works. 

Also side note for others who read this post. If you know of a fix please let me know as this would save lots of wasted time. Thanks!

After several hours I finally fixed the issue. . . . 

I created a second windows account on my computer & then reinstalled Origin/ME3 on the the new windows accounts.

Lauched the Game & everything is working so far. However everything on my Multiplayer is gone. (Levels, Credits Ect GONE)

After testing several things I'm 99.9% positive it had to with the computer name. ((SInce I changed my computer name few months back))

I know this is my own fault but still I'm shocked no one at EA could toss 2cents on this post. 

Cyrisal I would suggest trying these same steps as me.

1.) Create a second windows account

2.) Install Origin/ME3 on the new windows account.

If this does not work please let me know as I would like to help with this issue!

I was actually thinking about doing that myself, I had similar success with games which had issues, it was actually my next step, lets hope it works like it did for you mate.