According to the report at attachment ;Why does the Discrimination between NSX160B-3P-TMD-160A & EZC100H-3P-TMFIXED-32A is limited to 1250A Although there is no intersection between the Curves ???
This is due to the physical characteristics of the EZC circuit breaker which allow a discrimination only up to 1250A. To have a total discrimination with NSX, the ratio between the rating of the upstream and downstream breaker have to be 2.5 but in your case, it is only 160/100=1.6 (not 2.5).