Solid Element analysis Stress Summary

Dear Folks,

I am using Solid Elements for analysis & design block foundation for machine. As I understood from various literature that Sxx, Syy, Szz are normal stresses in the Global X, Y, Z directions respectively. The negative value would mean compressive stress and positive would mean tensile. Now if I am reading Solid center Stress summary where it is showing only maximum stress values as –ve values. That means its max compressive stress & no mention of any +ve (tensile) stress however if I check graphically solid stress contours there are traces of +ve (tensile) stresses.

Now my queries are:

1) Is there something wrong with summary table we are getting in staad ?

2) Should we refer summary only for max compressive stress ?

3) Should we refer only graphically solid stress contours for correct stress values ?

 STAAD.Pro Version used : STAAD.Pro CONNECT Edition - Version 21.00.02.30

If someone is having any clue about this then please reply, your response will be highly appreciated.

Thank you !