Setting G4NEUTRONHP_USE_ONLY_PHOTONEVAPORATION may solve the energy nonconservation problem, but as I described in the post https://geant4-forum.web.cern.ch/t/thermal-neutron-capture-gamma-spectra-give-major-disagreement-with-nndc-data-base-for-some-isotopes/6504 , the gamma spectrum is generally better (that is, closer in energies and relative intensities to NNDC data) if G4NEUTRONHP_USE_ONLY_PHOTONEVAPORATION is NOT set (=0). This is true in particular for 58Ni. Setting the flag to 0 does have some weird side effects, however.