peakDetect does not seem to work as expected

Question

I've added to my script from an example on the p5.js website.

I'd expect that an amplitude beyond 1.0 would satisfy the condition of their being a peak. I have set my amplitude range from 0 to 1.2, depending on the mouse y position. I can see that the amplitude reads out as 1.2, but the peakDectect.isDetected does not trigger.

fft.analyze was called, then fft is passed to peakDetect.update() so that it reads peakDetect.update(fft).

Code I'm using is below.

let fft, peakDetect, osc, lfo, playing, freq, amp;

function setup() {
  let cnv = createCanvas(300, 100);
  cnv.mousePressed(playOscillator);
  osc = new p5.Oscillator('sine');
  lfo = new p5.Oscillator('sine');
  filter = new p5.Filter();
  fft = new p5.FFT();
  peakDetect = new p5.PeakDetect();

  // chain
  lfo.disconnect();
  osc.disconnect();
  osc.connect(filter);
}

function draw() {
  background(220)
  freq = constrain(map(mouseX, 0, width, 40, 1000), 40, 1000);
  amp = constrain(map(mouseY, height, 0, 0, 1.2), 0, 1.2);

  if (playing) {
    // smooth the transitions by 0.1 seconds
    lfo.freq(2.9);
    osc.freq(freq, 0.1);
    osc.amp(amp, 0.1);
    filter.freq(1200);

    filter.res(14);
    // how many Hz should the LFO oscillate
    lfo.amp(1500);

    // connect the lfo
    filter.freq(lfo);

    let spectrum = fft.analyze();

    noStroke();
    fill(255, 0, 255);
    for (let i = 0; i < spectrum.length; i++) {
      let x = map(i, 0, spectrum.length, 0, width);
      let h = -height + map(spectrum[i], 0, 255, height, 0);
      rect(x, height, width / spectrum.length, h)
    }

    let waveform = fft.waveform();
    noFill();
    beginShape();
    stroke(255, 100, 0);
    for (let i = 0; i < waveform.length; i++) {
      let x = map(i, 0, waveform.length, 0, width);
      let y = map(waveform[i], -1, 1, 0, height);
      vertex(x, y);
    }
    endShape();

    // fft.analyze() has already been called.
    // check fft for peak detection. 
    peakDetect.update(fft);

    var ellipseWidth = 10;

    if (peakDetect.isDetected) {
      ellipseWidth = 50;
    } else {
      ellipseWidth *= 0.95;
    }

    noStroke();
    fill(0, 0, 0);

    ellipse(width / 2, height / 2, ellipseWidth, ellipseWidth);
  }

  fill(0, 0, 0);
  noStroke();
  text('tap to play', 20, 20);
  text('freq: ' + freq, 20, 40);
  text('amp: ' + amp, 20, 60);
}

function playOscillator() {
  osc.start();
  lfo.start();
  playing = true;
}

function mouseReleased() {
  // ramp amplitude to 0 over 0.5 seconds
  osc.amp(0, 0.2);
  playing = false;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.4.1/p5.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.4.1/addons/p5.sound.min.js"></script>