I observed that Nutanix machines showing as Physical instead of Virtual.
Is this default behaviour in Snow or its issue?
that's the current behavior, also described here.
Nutanix Acropolis hypervisor (AHV) support
This will be because SLM doesn't have any information about the Nutanix hypervisor. Oliver is right - you would need SNOW to create a new SIM connector for Nutanix so that it knows what are physical and virtual machines. SNOW may also have to add Nutanix as a hypervisor option in SLM too.
Retrieving data ...