Scintillation error running a simulation

Hi everyone,
I have been running a simulation (based on simulation B1) and encountered some issues with the scintillation behaviour.

My computer set-up is macOS Monterey, version 12.4, M1 chip. Geant4 has been re-installed, but it didn’t seem to help. I am currently using Geant4 version 11.0.3

The simulation runs fine if a line registering the Optical Physics registration in the Physics list is commenting out.

Has anyone encountered this issue previously or know how to fix it?

The error message is the following:

G4WT4 > → Event 0 starts with initial seeds (13049039,61775110).

G4WT4 > G4VParticleChange::CheckIt : the true step length is negative !! Difference: 0.0387463[MeV]

G4WT4 > opticalphoton E=3.34861e-06 pos=-0.000520943, 0.00242823, -0.191418

G4WT4 > -----------------------------------------------

G4WT4 > G4ParticleChange Information

G4WT4 > -----------------------------------------------

G4WT4 > # of secondaries : 0

G4WT4 > -----------------------------------------------

G4WT4 > Energy Deposit (MeV): 0

G4WT4 > Non-ionizing Energy Deposit (MeV): 0

G4WT4 > Track Status : StopAndKill

G4WT4 > True Path Length (mm) : -0.0387

G4WT4 > Stepping Control : 0

G4WT4 > First step in volume

G4WT4 > Mass (GeV) : 0

G4WT4 > Charge (eplus) : 0

G4WT4 > MagneticMoment : 0

G4WT4 > = : 0*[e hbar]/[2 m]

G4WT4 > Position - x (mm) : -0.521

G4WT4 > Position - y (mm) : 2.43

G4WT4 > Position - z (mm) : -191

G4WT4 > Time (ns) : -0.000178

G4WT4 > Proper Time (ns) : 0

G4WT4 > Momentum Direct - x : -0.243

G4WT4 > Momentum Direct - y : 0.113

G4WT4 > Momentum Direct - z : -0.963

G4WT4 > Kinetic Energy (MeV): 3.35e-06

G4WT4 > Velocity (/c) : 0.725

G4WT4 > Polarization - x : -0.634

G4WT4 > Polarization - y : 0.733

G4WT4 > Polarization - z : 0.246

G4WT4 >

-------- EEEE ------- G4Exception-START -------- EEEE -------

*** G4Exception : TRACK001

  issued by : G4VParticleChange::CheckIt()

Step length and/or energy deposit was illegal

*** Event Must Be Aborted ***

G4WT4 > G4Track (0x142653ea8) - track ID = 2, parent ID = 1

G4WT4 > Particle type : opticalphoton - creator process : Scintillation, creator model : Undefined

G4WT4 > Kinetic energy : 3.34861 eV - Momentum direction : (-0.242935,0.113321,-0.963401)

G4WT4 > Step length : -38.7463 um - total energy deposit : 0 eV

G4WT4 > Pre-step point : (-0.530356,2.43262,-191.455) - Physical volume : Sheet (Scintillator)

G4WT4 > - defined by : not available

G4WT4 > Post-step point : (-0.520943,2.42823,-191.418) - Physical volume : Sheet (Scintillator)

G4WT4 > - defined by : OpWLS - step status : 4

G4WT4 > *** Note: Step information might not be properly updated.

G4WT4 >

-------- EEEE -------- G4Exception-END --------- EEEE -------

There’s not enough information here to comment. What are your material property definitions for the material in question?