It seems likely. Given that the copper atoms prefer to form a non-superconducting material, it makes sense that there would be regions where the energy is just right to form the correct structure, and you get the incorrect structure everywhere else.

Given the way crystals grow, it then would follow that you'd get discontinuous crystals or grains within the material.

If we're taking bets, my money is on this exact thing happening. It'd explain the inconsistent results we've seen so far.