Cannot be able to retrieve data attribute when selectize is rendering

[FranRomero]

I am maintaining a project that is using selectize for its dropdowns. What I am trying to do is to retrieve data from data-* attributes so I can use that data when rendering, specifically, I want to pass through data attribute an image url so I can associate each option to its corresponding image.

According to docs, there is a dataAttr Selectize option, which default value is 'data-data' so I tried to include that attribute on HTML.

<option value="demovalue" data-data="{literal}{'demo': 'demo'}{/literal}">text</option>. I am using {literal} tags as I am using Smarty.

And I am trying to retrieve data like this:

$(this).selectize({
      plugins: selectizePlugins,
      hideSelected: true,
      copyClassesToDropdown: false,
      closeAfterSelect: true,
      allowEmptyOption: true,
      render: {
          option: function (data, escape) {
              console.log(data);
              return "<div data-url-image='" + escape(data.data) + "'>" + escape(data.text) + "</div>"
          }
      }
  });

I also tried adding dataAttr: 'data-data' to selectize options, but with the same result.

I am unable to get this data attribute on Javascript code. I saw a lot of examples on the internet even here on old tickets but I cannot it work.

Is it a bug?

NOTE: I am using v0.13.5 of Selectize and Smarty as PHP framework.