Gulp watch doesn't "feel" new files

Question

This is my watch.js as written by yeoman gulp-angular generator

'use strict';

var path = require('path');
var gulp = require('gulp');
var conf = require('./conf');

var browserSync = require('browser-sync');

function isOnlyChange(event) {
  return event.type === 'changed';
}

gulp.task('watch', ['scripts:watch', 'markups', 'inject'], function () {

  gulp.watch([path.join(conf.paths.src, '/*.html'), 'bower.json'], ['inject-reload']);

  gulp.watch([
    path.join(conf.paths.src, '/app/**/*.css'),
    path.join(conf.paths.src, '/app/**/*.scss')
  ], function(event) {
    if(isOnlyChange(event)) {
      gulp.start('styles-reload');
    } else {
      gulp.start('inject-reload');
    }
  });


  gulp.watch(path.join(conf.paths.src, '/app/**/*.jade'), ['markups']);

  gulp.watch(path.join(conf.paths.src, '/app/**/*.html'), function(event) {
    browserSync.reload(event.path);
  });
});

It works fine for already created files, but for some reason gulp.watch doesn't see the new ones (in particular .jade, but maybe also other types), eg.

myApp/src/components/header/headerView.jade

The only solution for me to run task as markup is to stop and restart gulp serve. Then gulp will recognizes changes in my .jade files