When adding or configuring a VM's network, no network is seen, even when no filters are applied: "No items found"
VMware vSphere
There are no networks on the host the VM resides on that are suitable for that VM.
Note that for a vSphere Distributed Switch (vDS), a single portgroup may be used by both a VM and a vmkernel adapter (e.g. vmk0) simultaneously. On a standard switch however, a portgroup can only be used by either a VM or a vmkernel adapter (but not both). If the VM in question resides on a host with only standard switches, there is likely no Virtual Machine portgroup that has been configured.
Create a Virtual Machine portgroup, or move the VM to a host that has a Virtual Machine portgroups configured.
See Port Group Configuration for Virtual Machines for guidance on configuring a Virtual Machine portgroup on a standard switch.