Your thread and info got me working with a MIDI Foot controller and a VST, thanks so much for getting me through the final mile. I'm not sure if I can post as many pics as I have created, but I'd like to give a step by step of how I got it working in case anyone else needs more info.
Sending from Rocktron MIDI Mate to Positive Grid BIAS FX VST in Studio One (v3.5.2 tested)
Grab the pizmidi MIDIProgramChange vst here: https://thepiz.org/pizmidi/pizmidi_x64.zip
Place files in Program Files\VSTplugins\PizMIDI
Notice settings for BIAS_FX external application. These are setup before opening Studio One. I set these up manually using the MIDI learn feature to setup the expression pedal and the MIDI PC Number to select a preset.
Open Studio One
Select External Device Setup
Add New Keyboard
Create New song
New audio track
Drag BIAS_FX VST to track
Drag MIDIProgramChange Instrument to create new track
Set Direct Input CH1 to MIDI Mate
Set Instrument track Output to BIAS FX_x64
Edit Mapping for Program Change – not sure is this was necessary, not needed for new songs since first working.
Now, I can create presets in BiasFX, set the preset edit to any number from 0-127 (MIDI Mate 1-128) and be able to change presets and use the expression pedal seamlessly during tracking. This has the added bonus of working in live scenarios where you want to run the band through an interface, run my guitar rig virtually and provide live monitoring from the cue mixes.