"As if that wasn’t bad enough, the Nighthawk had what developers at Lockheed called a “wing failure” problem. Its aerodynamics could sometimes force the wing and tail sections to come apart, an inherent flaw in the airframe design."
I never heard a single "developer" at Lockheed claim or state this.
The one wing failure, which was in Maryland, was due to faulty maintenance. They missed installing a number of fasteners in the structure and this started a cascading load path failure. The design was a bit complex and deemed beyond the scope of your average USAF mechanic to maintain, so that structure was redesigned.
The tail that came off was during initial flight test and again, due to maintenance.