In Forte 4, the full MIDI sync configuration is split into two settings, both accessed in the Rack Editor:

1.  Which MIDI Input port to listen for Sync - this is selectable on the MIDI Automation tab of Rack Editor

2.  Enable or disable Sync for each scene - this is selectable for each scene on the Scene tab of the Rack Editor (press "Details" to expand the options for each scene, then check or uncheck "Sync/BPM".

The MIDI sync port in rack editor simply selects the input port to listen to sync.  You also have to enable/disable Sync for a scene by moving to the Scenes tab, expanding the scene Detail, and checking "Sync/BPM".  This turns sync follow on or off per-scene.