grunt中livereload貌似冲突，无法正常工作。

Question

browserSync: {
      options: {
        notify: false,
        background: true
      },
      livereload: {
        options: {
          files: [
            '<%= config.app %>/{,*/}*.html',
            '.tmp/styles/*',
            '<%= config.app %>/images/{,*/}*',
            '.tmp/scripts/*'
          ],
          port: 9000,
          server: {
            baseDir: ['.tmp', config.app],
            routes: {
              '/bower_components': './bower_components'
            }
          }
        }
      },
      test: {
        options: {
          port: 9001,
          open: false,
          logLevel: 'silent',
          host: 'localhost',
          server: {
            baseDir: ['.tmp', './test', config.app],
            routes: {
              '/bower_components': './bower_components'
            }
          }
        }
      },
      dist: {
        options: {
          background: false,
          server: '<%= config.dist %>'
        }
      }
    }

watch: {
      bower: {
        files: ['bower.json'],
        tasks: ['wiredep']
      },
      babel: {
        files: ['<%= config.app %>/scripts/{,*/}*.js'],
        tasks: ['babel:dist']
      },
      babelTest: {
        files: ['test/spec/{,*/}*.js'],
        tasks: ['babel:test', 'test:watch']
      },
      gruntfile: {
        files: ['Gruntfile.js']
      },
      sass: {
        files: ['<%= config.app %>/styles/{,*/}*.{scss,sass}'],
        tasks: ['sass:server', 'postcss','browserSync:dist']
      },
      styles: {
        files: ['<%= config.app %>/styles/{,*/}*.css'],
        tasks: ['newer:copy:styles', 'postcss']
      }
    }

postcss: {
      options: {
        map: true,
        processors: [
          // Add vendor prefixed styles
          require('autoprefixer-core')({
            browsers: ['> 1%', 'last 2 versions', 'Firefox ESR', 'Opera 12.1']
          })
        ]
      },
      dist: {
        files: [{
          expand: true,
          cwd: '.tmp/styles/',
          src: '{,*/}*.css',
          dest: '.tmp/styles/'
        }]
      }
    }

grunt.registerTask('serve', 'start the server and preview your app', function (target) {

    if (target === 'dist') {
      return grunt.task.run(['build', 'browserSync:dist']);
    }

    grunt.task.run([
      'clean:server',
      'wiredep',
      'concurrent:server',
      'postcss',
      'browserSync:livereload',
      'watch'
    ]);
  });

yeoman自动创建的，运行grunt server后修改html可以自动刷新，修改并保存sass和js则完全没动静，看控制台显示的是执行完postcss后就没了。

第一次用求解决办法。