rajasekar, my suggestion is to open a support ticket. Let's have a support engineer take a look. You'll want to have diagnostics ready when you open your ticket, so that you can provide those immediately.
I have raised a case below is the response from TAC.
Case # - 00206275 We are not able to monitor CBQOS for cisco switch
The problem with the device from the most recent walk is this. While it has most of the OIDs, there is a hardware limitation Cisco confirmed and it's only tied to this model. The Class-map will always show 0 bytes for the OID:
Any one can share how to map CBQOS with class map in 3850 switch
