A Virtual Machine (VM) is not showing in the NSX Manager inventory and is therefore not visible for applying NSX policies, security groups, or Distributed Firewall (DFW) rules.
VMware NSX
The primary cause is that the Virtual Machine's Network Interface Card (NIC) is connected to a network that is not managed by NSX.
For NSX to discover a VM and include it in its inventory, the VM must be connected to an NSX-backed network segment (or logical switch). If the VM is connected to a standard vSphere Distributed Switch (vDS) or a standard switch port group that has not been prepared by NSX, the NSX Control Plane and Data Plane components (like nsx-vdl2) will not register the VM for management.
To ensure the VM is correctly registered in the NSX inventory, you must migrate the VM's network adapter to an NSX-managed network segment.