For port labels in a UDP symbol to be recognised as port names (and therefore populate the From Port and To Port fields in the Cable View and Cable Schedule), the text objects must be placed on one of the eight designated Circuit Path layers. Text on any other layer — including the Outline layer or any custom layer — is ignored for port name purposes.

The eight valid Circuit Path layers are:

• Audio Circuit Paths
• Control Circuit Paths
• Data Circuit Paths
• Lighting Circuit Paths
• Power Circuit Paths
• Video Circuit Paths
• User Circuit Paths 1
• User Circuit Paths 2

Resolution: open the affected UDP in the Symbol Editor. Select the port label text objects and change their layer to one of the Circuit Path layers above. If you want port labels to always be visible regardless of which circuit path layers are toggled, use User Circuit Paths 2. Save the UDP and allow it to re-sync.