This is a strange one. A package installed four weeks ago has been building nicely on the center four frames/foundation, just as expected. However when I pulled one of the center frames, the nearly full comb fell off as if it wasn't ever attached to the foundation. Yes, I do have fish line support lines running across all of the frames and that's always worked fine. The other frames were just fine, comb fully built, and attached to the foundation. All of the foundation is new and from the same box. To solve the immediate crisis I put the fallen comb of brood and honey in a new frame and held in place with rubber bands, much like would be done for placing feral comb into a hive.
Why would the bees build one-sided comb in withing a tiny fraction of an inch away from new foundation? And only on one side of one foundation? If I see evidence of this happening again on that foundation, clearly it will be trashed.