Gulp-sass with sourcemap in Firefox, how to get map correctly?

Question

Node.js

Good afternoon! But ... cold, damn it.
Mastering the gallop, the first steps.
Essence: You need to configure the scss sourcemap for the fox, but so that it sees the nesting.
I have a problem with fox not seeing nested tags in the debugger, giving it the line number of the parent.
New tags that are not nested in the parent in scss, the fox sees correctly.
On chrome, everything works perfectly, numbers the lines as it should.

gulp.task('scss', function(){
  return gulp.src('app/scss/*.scss')
  .pipe(sourcemaps.init())
    .pipe(sass({outputStyle: 'compact'}))
  .pipe(sourcemaps.write('app/maps'))
  .pipe(gulp.dest('app/css'))

});