Microwave phase is not working for a single-line spectrum

[stestoll]

The following should give two dispersion spectra (Exp.mwPhase=pi/2), but the one without Lorentzian broadening incorrectly returns the absorption spectrum.

clear, clc, clf

Exp.mwFreq = 9.5;
Exp.Range = [335 343];
Exp.mwPhase = pi/2;

Sys.lwpp = [1 0];
[B,spc_abs] = pepper(Sys,Exp);

Sys.lwpp = [1 0.1];
[B,spc_dis] = pepper(Sys,Exp);

plot(B,spc_abs,B,spc_dis);
legend('only Gaussian','incl Lorentzian')