Spot the bug - #124: Interactive Pulsing Blob

Why is my pulsing jelly blob pausing after one bounce?

const blob = document.querySelector('#jelly-blob');

const pulse = blob.animate(
  [{ transform: 'scale(1)' }, { transform: 'scale(1.4)' }],
  { duration: 400, direction: 'alternate', iterations: Infinity }
);

// Reversing direction mid-cycle on hover
blob.addEventListener('pointerenter', () => pulse.reverse());

Reply with what is broken and how you would fix it.