Gulp doesn't keep track of sass file updates, what's the problem?

Question

css

Hello. I am using jekyll to generate a static site. I also installed gulp https://github.com/shakyShane/jekyll-gulp-sass-bro... according to this article. But I have a slightly different structure. As a result, when editing html, the browser reloads the page and the changes are visible, but with scss everything is sad, it does not react at all, there are no errors either. Please see:
Structure:

Current gulpfile.js

// plugins for development
var gulp = require('gulp'),
  sass = require('gulp-sass'),
  prefix = require('gulp-autoprefixer'),
  plumber = require('gulp-plumber'),
  dirSync = require('gulp-directory-sync'),
  browserSync = require('browser-sync').create(),
  concat = require('gulp-concat'),
  cp = require('child_process');

// plugins for build
var purify = require('gulp-purifycss'),
  uglify = require('gulp-uglify'),
  csso = require('gulp-csso'),
  combineMq = require('gulp-combine-mq');

//var assetsDir = 'source/';
var outputDir = '_site/';
//var buildDir = 'build/';

//----------------------------------------------------Compiling
var messages = {
    jekyllBuild: '<span style="color: grey">Running:</span> $ jekyll build'
};


// Build the Jekyll Site

gulp.task('jekyll-build', function (done) {
    browserSync.notify(messages.jekyllBuild);
    return cp.spawn('jekyll', ['build'], {stdio: 'inherit'})
        .on('close', done);
});


// Rebuild Jekyll & do page reload

gulp.task('jekyll-rebuild', ['jekyll-build'], function () {
    browserSync.reload();
});

gulp.task('sass', function () {
  gulp.src('/css/main.scss')
    .pipe(plumber())
    .pipe(sass())
    .pipe(prefix('last 15 versions'))
    .pipe(gulp.dest('/_site/css'))
    .pipe(browserSync.stream());
});

// livereload and open project in browser

gulp.task('browser-sync', ['sass', 'jekyll-build'], function() {
  browserSync.init({
    port: 1337,
    server: {
      baseDir: outputDir
    }
  });
});

//---------------------------------watch

// Watch scss files for changes & recompile
// Watch html/md files, run jekyll & reload BrowserSync

gulp.task('watch', function () {
    gulp.watch('/_sass/**/*.scss', ['sass']);
    gulp.watch(['*.html', '_layouts/*.html', '_includes/*.html', '_posts/*'], ['jekyll-rebuild']);
});


// Default task, running just `gulp` will compile the sass,
// compile the jekyll site, launch BrowserSync & watch files.

gulp.task('default', ['browser-sync', 'watch']);

Answer 1

remove the leading slash from everywhere, with it the node takes an absolute path, and you need a relative one

Answer 2

You need to either show in gulpa where your mess is coming from, or make a path in scss

@import "../_sass/base/variables.sass";
...