EA has told Eurogamer it hopes to solve the Army of Two 2 downloadable content problems "soon".
But for now, a week after release, add-on Chapters of Deceit still has faulty Achievements and Trophies.
"There is a known issue affecting Achievements in an Army of Two DLC pack. We are looking into a solution and hope to provide an update soon," said an EA spokesperson, relaying a message from developer EA Montreal.
Chapters of Deceit adds two new campaign maps to Army of Two: The 40th Day, but doesn't stuff enough content to warrant the 800 Microsoft Point (£6.80/9.60) or £6.30/7.99 price.
Eurogamer's Chapters of Deceit review goes into more detail.