In ultrarelativistic heavy-ion collisions the Lorentz-contracted electromagnetic fields of the nuclei are a source of high-energy quasireal photons which can produce muon pairs via the process $\ensuremath{\gamma}+\ensuremath{\gamma}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}+{\ensuremath{\mu}}^{\ensuremath{-}}$. In hadronic Pb+Pb collisions the two leptons in the final state provide a sensitive probe of the quark-gluon plasma created in the Pb+Pb collision or the strong magnetic fields that the plasma generates. This work presents new measurements by the ATLAS collaboration at the LHC of the Pb+Pb collision centrality dependence of the angular decorrelation of muon pairs created via the $\ensuremath{\gamma}\phantom{\rule{0}{0ex}}\ensuremath{\gamma}$ process. Comparisons of the results to theoretical calculations suggest that the observed decorrelation in more central collisions results from an initial-state broadening of the photon transverse momenta and not from the interaction of the muons with the plasma or its magnetic field.