webpack@4.41.5下watch模式不生效

Question

在mac系统下为啥文件变动使用watch命令不生效？

webpack --config webpack.config.prod.js --watch --mode production

webpack.config.prod.js也非常简单

const path = require('path');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const ManifestPlugin = require('webpack-manifest-plugin');

module.exports = {
  entry: './src/index.js',
  output: {
    filename: 'main.js',
    publicPath: '',
    path: path.resolve(__dirname, 'build')
  },
  devtool: 'source-map',
  watchOptions: {
    ignored: /node_modules/
  },
  module: {
    rules: [
      {
        test: /\.(js|jsx)$/,
        exclude: /node_modules/,
        use: {
          loader: 'babel-loader'
        }
      },
      {
        test: /\.(sa|sc|c)ss$/,
        use: [
          {
            loader: MiniCssExtractPlugin.loader,
            options: {
              hmr: process.env.NODE_ENV === 'development'
            }
          },
          'css-loader', // translates CSS into CommonJS
          'sass-loader' // compiles Sass to CSS, using Node Sass by default
        ]
      }
    ]
  },
  plugins: [
    new MiniCssExtractPlugin({
      filename: '[name].css',
      chunkFilename: '[id].css'
    }),
    new ManifestPlugin()
  ]
};