It seems like independent deltas don't work in .then() functions.

I am trying to create a jump animation using this code:

const circle = new mojs.Shape({
  top: 40,
  left: 40,
  y: {
    0: 100,
    easing: "cubic.out"
  },
  x: {
    0: 20,
    easing: "linear.none"
  },
  radius: 40,
  duration: 250,
}).then({
  y: {
    100: 0,
    easing: "cubic.in"
  },
  x: {
    20: 40,
  }
});

When adding any of the independent delta properties specified in https://mojs.github.io/api/modules/html/#independent-deltas, the .then() is ignored altogether.

Am I using it improperly or is there any fix for this?