An extensive physical property of matter is a property that depends on the amount of substance present, such as mass, volume, weight, and length. These properties are additive; for example, the mass of two objects is the sum of their individual masses.
In CPE the total mass of the universe simply is unbounded from the general perspective, but in a localized harmonic of mass in space time mass becomes bounded by the containment in the geometric oscillation.
In General Relativity the additive nature of volumes of mass is the stress-energy-momentum tensor describing the geodesics of motion.
In QM mass also behaves additively but the perspective orientation is shifted. The sum over paths method is this additional property of Mass within the model. Total Mass of the system is distributed throughout the geometric container and by summing all potential paths they are added and become the Total Mass of the system. We must sum, and matter must explore all paths, to reach Total Mass = 1 as leaving any of the potential paths out just because it is not locally observed would leave us with incorrect illogical representation of Mass.