Could someone please explain the Unison Screen?

So I have a 4 Chord Drone and the Digitone is cutting the release.
Digitone is set to 8 Locked Voices at that Track but just 4 Voices are playing.
The Notes aren’t overlapping so why is the release cut. AENR set to not retrigger.

What does [Func]+Unsion do? The symbol gets blue.

What does “Cycle” “Track” “low” “High” mean? Polyphony cut if it runs out of voices?