So I’m guessing you have also duplicated the related code, in particular that relating to the level summary in UTWorldSettings.cpp? If so, when you package, the cooker will be loading these maps into memory, which will trigger the summary creation, and then serializing them, cooked. So to me, it makes sense that all your maps will be behaving the same in the cooked build.
Afraid I can’t help with the crash. It looks like some kind of serialization mismatch, where what got written to disk isn’t what the code doing the deserializing is expecting. Hard to say more than that.