To answer my own question.. It may be, that I misread the manual - or screwed something else up in my audio MIDI Setup... but I have Program Change messages working. What I discovered, is that all other CC messages can travel to my Pigments 3 standalone instance.. on various MIDI Channels, with no fail. Program Change messages however.. only work on MIDI Channel 1. There may be something I have wonky in my audio MIDI setup, or elsewhere - as this is effecting all my Arturia soft synths similarly. Program Changes... come down MIDI Channel 1. Nowhere else. So - Program Change messages mapped using MIDI Channel 1 = a win. Still hoping, there is something else wrong.. as I am keen to sending Program Change messages to any Arturia soft synth (and I am using different channels for them). This may be something that only happens on the standalone instances of the Arturia synths I am using, or something else??