Hi Tim, Fingered mode as you probably know requires at least 3 notes in order to specify the chord.
The Basic mode requires 1 note for a major chord; 2 notes for a minor chord (Root note plus any black key); 2 notes for a 7th chord (Root note plus any white key) PLUS if you play 3 notes or more whilst in Basic mode, it will then produce the same chords as the Fingered mode.
John