In one of my current cities, I have been trying to add stations and extend one of my subway lines. However, when trying to drag the subway line to the end of the extension, it 'can't find the path'. It seems like I would have to demolish and rebuild my entire subway system to add any new stops to my existing system. Is this some kind of bug? I am using the MOM for the subway system, I don't understand why the pathfinding cannot identify the new stations.