Actually this is not possible because the interface is running 64 virtual functions (i.e. 64 VMs) traffic on a single physical interface. Mirroring will create a huge load of packets on CPU.

Main query is - why I am not able to see it?

It’s all depends which NICs you are using, couple of NICs supports tcpdump on hypervisor but most of common sriov nics you can’t filter tcpdump on sriov VF NICs , data goes from additional driver vf pci and there is separation between physical function and virtual functions.

I think you're right because we are using Mellanox NICs whose driver does not have this capability