Mod Envelope 4 can be monophonic or polyphonic. When you select the MOD 4 tab in the Envelope Zoom, you will see a small button, labeled “P” to the right of the tab.
Engaging it makes Mod Envelope 4 polyphonic, meaning each note will trigger it’s own envelope, instead of all notes sharing the same one.
To demonstrate this, right click on the Fine Pitch knob and select “Modulate with Envelope.” Next, select Mod Envelope 4 as a source in the Modulation sidebar, then load the preset “00. Default ADSR” from the Envelope Presets menu. In monophonic mode (“P” OFF), play and hold Middle C and then play C one octave below. You’ll notice when you play the second note, Middle C is also modulated. Release both notes, engage the polyphonic envelope (“P” ON) and try it again. When you play both notes in a similar way, each one will be modulated independently.