Missing prefixes with postcss / autoprefixer on webpack 3

Question

I am using postcss, autoprefixer and extract-text-webpack-plugin with Webpack 3, but when compiled I am missing prefixes. The compiled css only contains the -webkit prefix and not the -ms and -moz prefixes.

I am not sure what I am doing wrong.

My config:

module: {
        rules: [
            {
                test: /\.js$/,
                exclude: /node_modules/,
                use: 'babel-loader'
            },
            {
                test: /\.s[ac]ss$/,
                loader: ExtractText.extract({
                    use: [
                        {
                            loader: 'css-loader',
                            options: {
                                sourceMap: true
                            }
                        },
                        {
                            loader: 'postcss-loader',
                            options: {
                                ident: 'postcss',
                                sourceMap: true,
                                plugins: () => [autoprefixer()]
                            }
                        },
                        {
                            loader: 'sass-loader',
                            options: {
                                sourceMap: true
                            }
                        }
                    ],
                    fallback: 'style-loader',
                })
            },
            {
                test: /\.(eot|svg|ttf|woff|woff2)$/,
                use: 'file?=name/fonts/[name].[ext]'
            },
            {
                test: /\.(jpe?g|png|gif|svg)$/i,
                use: [{
                    loader: 'file-loader',
                    options: {
                        name: '[name]-[hash:8].[ext]',
                        pluginPath: BUILD_DIR + '/images/',
                        outputPath: BUILD_DIR + '/images/'
                    }
                }]
            }]
    },

And my browserlist in package.json contains:

"browserslist": [
    "defaults",
    "not ie < 9",
    "last 2 versions"
  ],