webkitRelativePath is null

[elicat]

Good morning everyone,
there is a way to enjoy the property webkitdirectory in element html type file

<input type="file" id="filepicker" name="fileList" webkitdirectory multiple />

If I use it outside a QtWebengine project I can select the chosen folder if it contains at least one file. Example code js : https://codepen.io/simevidas/pen/ZJjmWG

picker.addEventListener('change', e => {
  for (let file of Array.from(e.target.files)) {
    let item = document.createElement('li');
    item.textContent = file.webkitRelativePath;
    listing.appendChild(item);
  };
});

The same javascript function in a page in qtwebengine returns the null value:

1: File
lastModified: 1692711081402
lastModifiedDate: Tue Aug 22 2023 15:31:21 GMT+0200 (Ora legale dell’Europa centrale) {}
name: "alertblack.png"
size: 895
type: "image/png"
webkitRelativePath: ""

Does anyone know if I need to set something at project startup? Does the problem solve?
Thank you