The Ports tab of a vSphere Distributed Switch (vDS) does not display all ports.
VMware vCenter Server 6.x - 7.x
This is an expected behavior in vCenter Server 6.x-7.x.
For performance reasons, only the first 2,000 ports are shown if viewing the Ports tab for the entire vDS.
In vCenter Server 8.0 and beyond, the ports are now paginated; enabling viewing of all ports
Select the port group containing the ports you are interested in (instead of the entire vDS), then view the Ports tab.