Hide empty widget – not working

Hi,
I want to hide the widget when empty, I added the following code to functions.php theme file:

add_filter( ‘black_studio_tinymce_hide_empty’, ‘__return_true’ );

But the widget is still displayed (it contains a shortcode, which returns empty result).

I’m running on php7, WP 4.5.3

Any idea?
Thanks.

https://ww.wp.xz.cn/plugins/black-studio-tinymce-widget/