In Ember.js, ID of the sub-array elements are not passed within ajax put

I do a put call in ember.js and I am passing an object which contains an array. The element's id in this array are never passed to the backend, yet they do exist in the object.

I do a put call using

this.ajax.put('path', { data: object }.then();

The object that I am passing as the data has an array (example of the DTO).

object = {
  "array": [
    {
      "id": 0,
      "prop1",
      "prop2",
      "etc..."
    }
  ],
  "prop1",
  "prop2",
  "etc..."
}

The way that I construct each object from the array is by using

let objectArray = get(object, 'array');
let elementInObjectArray = //ajax call to get the element to add;
objectArray.pushObject(store.createRecord('element-in-object-array', { 
   id: elementInObjectArray.id,
   prop1: elementInObjectArray.prop1,
   etc...
})

Just before my put call, I log the id of the object.array.element.id, and they are defined and accessible (as string). (See image)

Yet, this id is never passed to the backend, and then I get a 404 from the server because the id is the primarykey. (See image of my put request payload)

I know that ember always return a string as an id when creating a record, but I don't think this is the reason why it fails since I would probably get more like a 400 for bad formatting. Right now, the id is just never passed.

How can I make sure that the id of the array element is passed in the call?