Chemically induced dynamic nuclear polarization is a ubiquitous phenomenon in photosynthetic reaction centers. The relevant nuclear spin observables are a direct manifestation of the radical-pair mechanism. We here use quantum trajectories to describe the time evolution of radical-pairs, and compare their prediction of nuclear spin observables to the one derived from the radical-pair master equation. While our approach provides a consistent description, we unravel a major inconsistency within the conventional theory, thus challenging the theoretical interpretation of numerous CIDNP experiments sensitive to radical-pair reaction kinetics. (C) 2015 Elsevier B.V. All rights reserved.