The (Sig_rr) normal stress is computed for a solid element by averaging the Normal_Z stresses at each grid.
Sig_rr = Sig_Z Average (G1:G8)
This stress is passed directly into the Flatwise Tension analysis, the panel bending moments are not used to determine the Sig_rr. If the average stress is compressive, the Flatwise tension analysis should be disabled.
If you have a case that is behaving otherwise, could you please send me the example.