Gulp 4: set up automatic page refresh?

Question

gulp.js

Good afternoon.
Today I personally encountered the problem of the updated "gulp". It just so happened that I set myself version 4 ... And away we go. A lot of mistakes, everything is stupid, slows down, lags.
But I was not at a loss, I read the solutions. This one was especially helpful: https://stackoverflow.com/questions/39665773/gulp-...
And no more errors. There literally brackets [ ] should be changed.
But auto update doesn't work. That is, I write changes to the sass file, but compilation to css does not occur. If the problem was in the sass task, shouldn't I get an error?
I feel like the problem is somewhere here:

gulp.task('watch', gulp.series('browser-sync', 'sass', function() {
  gulp.watch('app/sass/**/*.sass', gulp.series('sass'));
}));

And here is the whole code:

var gulp        = require('gulp'),
  sass        = require('gulp-sass'),
  browserSync = require('browser-sync');

gulp.task('sass', function() {
  return gulp.src('app/sass/**/*.sass')
  .pipe(sass())
  .pipe(gulp.dest('app/css'))
  .pipe(browserSync.reload({stream: true}))
});

gulp.task('browser-sync', function() {
  browserSync({
    server: {
      baseDir: 'app'
    },
    notify: false,
  });
});


gulp.task('watch', gulp.series('browser-sync', 'sass', function() {
  gulp.watch('app/sass/**/*.sass', gulp.series('sass'));
}));

Need your help
PS It is necessary that when you run gulp watch, with any changes, the page is automatically updated and shows the result.

Answer 1

Might come in handy for someone. Before making any edits, check if you have a body tag on your page. I accidentally forgot it and stopped updating. Stupid mistake, but you can break the brain. )))

Answer 2

Try like this:

gulp.task('watch', gulp.parallel('browser-sync', 'sass', function() {
  gulp.watch('app/sass/**/*.sass', gulp.parallel('sass'));
}));