If suppressEnergy is left to its default value of 0 in text driven simulations, this will prevent loading of secondary electrons subject to an E field which would accelerate it into the boundary. The user can try switching off the sources of E fields to check if the emission is correct. Due to space-charge it’s quite likely that many of the secondary electrons will then experience the field and be driven into the boundary, having their emission suppressed. In other words they will not appear in the simulation. Setting suppressEnergy to a large value like \(1.e20\) should address the issue.
See also the descriptions of Secondary Electron Emitter and secElec in the VSim Reference Manual.