Autoprefixer not working with neutrino and webpack

Question

I am trying to enable CSS support for older browsers and introduce cross-compatibility. I am using autoprefixer as processor along with postcss-load-config.

The expected CSS should include browser compatibility for browsers like Safari or Mozilla, but the builds do not add the required CSS.

.neutrinorc.js

module.exports = {
  ...

  module: {
    rules: [
      { 
        test: /\.css$/, 
        use: ['style-loader', 'css-loader', 'postcss-loader'] 
      },
    ]
  }

  ...
};

package.json

{
...

"postcss": {
    "parser": "sugarss",
    "map": false,
    "plugins": {
      "postcss-plugin": {}
    }
  }

...
}

webpack.config.js just uses neutrino to create an instance of webpack using neutrino const config = neutrino().webpack(); and sets aliases for folders.