Laravel query builder doesn't work with COALESCE

Hi all, This query works perfectly and return values in both subject and body_html columns.

SELECT translations.id, COALESCE(locale.subject, fallback.subject) as subject, COALESCE(locale.body_html, fallback.body_html) as body_html 
FROM translations 
LEFT JOIN translations AS locale ON locale.translatable_id = translations.translatable_id AND locale.translatable_type = translations.translatable_type AND locale.locale = "fr" 
LEFT JOIN translations AS fallback ON fallback.translatable_id = translations.translatable_id AND fallback.translatable_type = translations.translatable_type AND fallback.locale = "en" 
WHERE translations.translatable_id = 1 AND translations.translatable_type = "App\Models\Email" 
LIMIT 1;

Now the same with the Laravel query builder, (note: the variables used here contain the correct values):

return Translation::selectRaw('translations.id,'.
     'COALESCE(locale.subject, fallback.subject) AS subject,'.
     'COALESCE(locale.body_html, fallback.body_html) AS body_html')
  ->from('translations')
  ->where('translations.translatable_id', $this->id)
  ->where('translations.translatable_type',  get_class($this))
    ->leftJoin('translations AS locale', function ($join) use($locale) { 
          $join->on('locale.translatable_id', 'translations.translatable_id')
                     ->where('locale.translatable_type', 'translations.translatable_type')
                     ->where('locale.locale', $locale);
    })->leftJoin('translations AS fallback', function ($join) {
                $join->on('fallback.translatable_id', 'translations.translatable_id')
                     ->where('fallback.translatable_type', 'translations.translatable_type')
                     ->where('fallback.locale', config('app.fallback_locale'));
})->first();

The id column value is correct but subject and body_html values are empty.

What's wrong with that query ?