npm - Gulp - watch not 'watching' sass -

i started using gulp projects have little problem.
browerssync works fine on watch, sass not compile on watch (manualy works fine). here gulpfile.js - problem?

var gulp = require('gulp'); var sass = require('gulp-sass'); var imagemin = require('gulp-imagemin'); var browsersync = require('browser-sync').create(); var cache = require('gulp-cache');  gulp.task('sass', function(){     return gulp.src('./dev/sass/*.scss')         .pipe(sass()) // using gulp-sass         .pipe(gulp.dest('./assets/css'))         .pipe(browsersync.reload({             stream: true         })) });  gulp.task('images', function(){   return gulp.src('./dev/images/**/*.+(png|jpg|jpeg|gif|svg)')   // caching images ran through imagemin   .pipe(cache(imagemin({       interlaced: true     })))   .pipe(gulp.dest('./assets/images')) });  gulp.task('browsersync', function() {     browsersync.init({         server: {             basedir: ''         },     }) });  gulp.task( 'watch', ['browsersync', 'sass'], function () {     gulp.watch( './dev/sass/*.scss', ['sass'] );      gulp.watch( '*.html', browsersync.reload ); }); 

edit: here log console:

d:\esports-ground\portal>gulp watch (node:9416) fs: re-evaluating native module sources not supported. if using graceful- fs module, please update more recent version. [21:49:16] using gulpfile d:\esports-ground\portal\gulpfile.js [21:49:16] starting 'browsersync'... [21:49:16] finished 'browsersync' after 13 ms [21:49:16] starting 'sass'... [bs] 1 file changed (style.css) [21:49:16] finished 'sass' after 39 ms [21:49:16] starting 'watch'... [21:49:16] finished 'watch' after 12 ms [bs] access urls:  -------------------------------------        local: http://localhost:3000     external: http://192.168.56.1:3000  -------------------------------------           ui: http://localhost:3001  ui external: http://192.168.56.1:3001  ------------------------------------- [bs] serving files from: ./