It seems I have found a bug in WordPress SEO: Using the "à" character makes any text disappear. The cause to this is in the following code:
wpseo-functions.php :: 41
// Let's see if we can bail super early. if ( strpos( $string, '%%' ) === false ) return trim( preg_replace('/\s+/',' ', $string) );
This regular expression makes any "à" character into those "?" signed chars and...
class-frontend.php :: 590
echo '<meta name="description" content="'.esc_attr( strip_tags( stripslashes( $metadesc ) ) ).'"/>'."\n"; else if ( current_user_can('manage_options') && is_singular() )
...when you put string with the "?" signed chars in
esc_attr() the result is an empty string.
The "à" character is very important in portuguese. "on sale" in portuguese for instance, is written "à venda".