Shortcode in Header Text Not working

I’m unable to get the Header Options | Header Text to return my short code. The shortcode works in the rest of the site.

I’ve tried to hack line 1365 of mobmenu.php with:

//  $output .= $header_text;

$var_title = do_shortcode( '[landing_page_title]') ;
$output .= $var_title ;

This returns blank however this method works throughout the rest of the site.

Thank you in advance for any assistance.

~ Bill

https://ww.wp.xz.cn/plugins/mobile-menu/