Webpack Mix不会在Laravel 5.6中更新文件

Question

webpack.mix.js

mix.sass('resources/assets/sass/frontend/app.scss', 'public/css/frontend.css')
    .sass('resources/assets/sass/backend/app.scss', 'public/css/backend.css')
    .styles([
        'public/js/select2/select2.css',
        'public/css/bootstrap.min.css',
        'public/css/custom-style.css',
    ], 'public/css/backend-custom.css')
    .js([
        'resources/assets/js/backend/app.js',
        'resources/assets/js/plugin/sweetalert/sweetalert.min.js',
        'resources/assets/js/plugins.js'
    ], 'public/js/backend.js')
    .scripts([
        "node_modules/moment/moment.js",
        "node_modules/select2/dist/js/select2.full.js",
        "public/js/bootstrap-datetimepicker.min.js",
    ], 'public/js/backend-custom.js')
    .webpackConfig({
        plugins: [
            new WebpackRTLPlugin('/css/[name].rtl.css')
        ]
    })
    .version();

我也没有运气尝试过：npm run watch-poll。

PHP版本：7.2.4
Laravel：5.6.26
节点：10.9.0
NPM：6.4.0