Symptom:
** Following CLI  shows are not updated with SN or FEX type etc

show module fex xxx
show inventory fex xxx


Example:

N9K-2# sh module fex 101

FEX Mod Ports Card Type                          Model              Status.
--- --- ----- ---------------------------------- ------------------ -----------
101  1  48    Unknown Module                     N2K-C2248TP-1GE    ok


show inventory fex 101 
NAME: "FEX 101 CHASSIS",  DESCR: "GE  CHASSIS"                           
PID: GE                  ,  VID:     ,  SN:                      

NAME: "FEX 101 Module 1",  DESCR: " Supervisor"                           
PID: GE                  ,  VID:     ,  SN:

Conditions:
When FEX is connected to Nexus 9300 switch