AFAIK, The only format that has the concept of MIDI FX is AU.
So, when deploying MIDI FX, the solution that worked for me so far was to declare the plugin as both a Synth and MIDI FX:
IS_SYNTH TRUE NEEDS_MIDI_INPUT TRUE NEEDS_MIDI_OUTPUT TRUE IS_MIDI_EFFECT TRUE
That’s totally fine for VST/VST3 as you can open the plugin as a synth and route the MIDI to another track.
However, that makes the plugin completely fail and not produce MIDI in AAX under Pro Tools.
If I set
FALSE it works fine in Pro Tools, but fails in Logic under AU.
Is it possible to completely ignore
IS_MIDI_EFFECT for AAX?