gulp runs just once, make it continue to watch

When running gulp. It runs and compiles SASS one time. How can I adjust the watch so that it continues watching for changes. Do I need to add usePolling: true or usegulp.series. I am following the directions exactly from the Bootstrap 4 SASS - Barrio Starter Kit →

My setup:
drupal core 9.1.10
bootstrap_barrio 8.x-4.33
bootstrap_sass 8.x-1.13
node v12.22.1
npm 6.14.12
gulp CLI version: 2.3.0
gulp Local version: 4.0.2
Vagrant on Windows using a Redhat 7 virtual machine

My gulpfile:

        let gulp = require('gulp'),
          sass = require('gulp-sass'),
          sourcemaps = require('gulp-sourcemaps'),
          cleanCss = require('gulp-clean-css'),
          rename = require('gulp-rename'),
          postcss = require('gulp-postcss'),
          autoprefixer = require('autoprefixer'),
          browserSync = require('browser-sync').create()

        const paths = {
          scss: {
            src: './scss/style.scss',
            dest: './css',
            watch: './scss/**/*.scss',
            bootstrap: './node_modules/bootstrap/scss/bootstrap.scss'
          },
          js: {
            bootstrap: './node_modules/bootstrap/dist/js/bootstrap.min.js',
            jquery: './node_modules/jquery/dist/jquery.min.js',
            popper: 'node_modules/popper.js/dist/umd/popper.min.js',
            popper: 'node_modules/popper.js/dist/umd/popper.min.js.map',
            dest: './js'
          }
        }

        // Compile sass into CSS & auto-inject into browsers
        function styles () {
          return gulp.src([paths.scss.bootstrap, paths.scss.src])
            .pipe(sourcemaps.init())
            .pipe(sass().on('error', sass.logError))
            .pipe(postcss([autoprefixer({
              browsers: [
                'Chrome >= 35',
                'Firefox >= 38',
                'Edge >= 12',
                'Explorer >= 10',
                'iOS >= 8',
                'Safari >= 8',
                'Android 2.3',
                'Android >= 4',
                'Opera >= 12']
            })]))
            .pipe(sourcemaps.write())
            .pipe(gulp.dest(paths.scss.dest))
            .pipe(cleanCss())
            .pipe(rename({ suffix: '.min' }))
            .pipe(gulp.dest(paths.scss.dest))
            .pipe(browserSync.stream())
        }

        // Move the javascript files into our js folder
        function js () {
          return gulp.src([paths.js.bootstrap, paths.js.jquery, paths.js.popper])
            .pipe(gulp.dest(paths.js.dest))
            .pipe(browserSync.stream())
        }

        // Static Server + watching scss/html files
        function serve () {
          browserSync.init({
            proxy: 'http://orgex1',
            open: false,
          })

          gulp.watch([paths.scss.watch, paths.scss.bootstrap], styles).on('change', browserSync.reload)
        }

        const build = gulp.series(styles, gulp.parallel(js, serve))

        exports.styles = styles
        exports.js = js
        exports.serve = serve

        exports.default = build

Result when running gulp:

[vagrant@vagrant6 presentation]$ gulp
[15:47:33] Using gulpfile /var/www/html/orgex1/web/themes/custom/presentation/gulpfile.js
[15:47:33] Starting 'default'...
[15:47:33] Starting 'styles'...
[15:47:37] Finished 'styles' after 3.62 s
[15:47:37] Starting 'js'...
[15:47:37] Starting 'serve'...
[Browsersync] 3 files changed (bootstrap.min.js, jquery.min.js, popper.min.js.map)
[15:47:37] Finished 'js' after 56 ms
[Browsersync] Proxying: http://orgex1
[Browsersync] Access URLs:
----------------------------------
Local: http://localhost:3000
External: http://10.0.2.15:3000
----------------------------------
UI: http://localhost:3001
UI External: http://localhost:3001
----------------------------------