The easiest thing would be to turn off "Vol/Exp" in the Zone Settings (for each PART).

This should stop transmitting these MIDI messages to Korg.

The other method if you want to use Mod/Control to set volumes - then you'd have to do a lot of programming.

https://www.yamahasynth.com/ask-a-question/how-to-turn-off-foot-controller-1-to-designated-parts

You could change the Performance Common CC settings for FC1 to something other than CC#11. Something your Korg would "throw away". And then reconfigure that same Performance so that Motion Control (Mod Control assignments) are used when using FC1 as the source. This is another option. I included the link above as context to show graphically how the expression pedal can be configured.

I want to turn OFF the volume pedal affecting the Kronos. In other words, I want the volume pedal to work for the MODX but not the Kronos. I realize I need to go to Mod/Control of that particular part and turn off "volume" and/or FC1 (since FC1 is where I have my volume pedal plugged into).

Not working.

Then that is a problem. Each Zone slot should be set to control a different MIDI Channel. We’ll assume you meant the MODX Parts are on Channel 1 and 2 and slots 3 and 4 are set to trigger the Kronos... You do not mention what MIDI Channels the two Kronos Parts are set to receive On. This is critical.

It would be impossible to tell you why turning “VOL/EXP” = OFF is “not working” for the Kronos controlled Zones without ensuring the discreet channel used for communication.

We know that Parts 1 and 2 (those addressing the internal tone generator) are occupying Channels 1 and 2, respectively. No Transmit Channel setting is necessary... Part 1 uses Ch1, Part 2 occupies Ch2... this is automatic for internal Parts
What “TRANSIT CH” are Zone slots 3 and 4 set to...?

A Part/Zone slot designated for an external device must have an internal MODX Part assigned to it, then within the “Zone Settings” set the “INT SW” (Internal Switch) = Off, and set the “Transmit Ch” to match the Receive Channels required to trigger the Kronos.

Let us know.

Extra Credit:
You have several options concerning this setup.
Turning the “Vol/Exp” Receive Switch to Off will make that Part/Zone slot ignore cc7 and cc11, specifically.
Turning the “FC1” Receive Switch to Off will make the Part/Zone slot ignore the Foot Controller 1 when it is assigned to a cc other than 7 or 11. Say you set FC1 to cc4 Foot Control... this can be set to control a different selected parameter within each Part... say you wanted to control internal Parts 1 and 2 with your FC1 = cc4... within the Part you would set Destination = VOLUME, Source = FOOT CTRL 1

There is no function that is automatically associated with cc4 (as there is with cc7 Volume, and cc11 Expression). cc7 and cc11 are universal throughout MIDI.

If the audio output of the Kronos is plugged into the MODX A/D IN, you can assign control of its Volume within the Motion Control Synthesis Engine... meaning you can use the Super Knob to morph (control the balance) between the internal MODX and the external Kronos Parts (same as if the external slots were apart of the MODX).

The easiest thing would be to turn off "Vol/Exp" in the Zone Settings (for each PART).

This should stop transmitting these MIDI messages to Korg.

That would have been the ticket...if it worked 🙁

As for the channels, The Part in the Kronos that I want to change the volume pedal is PART 3 and it is set to channel 3.

I don't want to turn off FC1 altogether because I want to control the volume on the MODX, just not the specific part in the KRONOS.

I've turned off every Switch off i could find for that part and it just doesn't work.

Have you changed the FC1 CC from 11 to something Kronos ignores (there are many choices)?