NX Qualified fitting port is missing once the library part is placed.

A fitting port has been created in the library part end form. 
However, the fitting port can't be added by "Place End Form".
How to add the fitting port created in the library part?

Solution

It is not possible to have a fitting port as you expect with Endforms.
Because it is not like typical fitting part placement.
The placement modifies an existing stock by adding a feature (Stock End form)

Hardware/Software Configuration

Platform: INTEL
OS: windows
OS Version: 1064
Product: NX
Application: ROUTING_MECH
Version: V1953
Function: TOOLS

Ref: 002-8566900