Saliom

Hello there,

With Lightbox Plus Colorbox, add that code in your functions.php to exclude the script which have a conflict with WP Deferred JavaScripts:

// Don't defer this script.
add_filter( 'do_not_defer', 'exlude_lightbox_scripts' );
function exlude_lightbox_scripts( $do_not_defer ) {
		$do_not_defer[] = 'jquery-colorbox';
		return $do_not_defer;
}

You can try to search every script loaded in your plugin by the way of “wp_enqueue_script()” to exclude the scripts one by one to find the one that should not be differed.

P.S: I found all of that in the readme.txt of the plugin.