Fix CPT Menu highlight

functions.php

//Fix CPT menu highlight
	
	add_filter( 'nav_menu_css_class', 'namespace_menu_classes', 10, 2 );
	
	function namespace_menu_classes( $classes , $item ){
		$Cpost = 'portfolio'; //Define CPT name
		$CpostMenu = get_bloginfo('url').'/'.$Cpost.'/'; //Define CPT Menu URL
		
		if ( get_post_type() == $Cpost || is_archive( $Cpost ) ) {
			// remove that unwanted classes if it's found
			$classes = str_replace( 'current-page-parent', '', $classes );
			// find the url you want and add the class you want
			if ( $item->url == $CpostMenu ) {
				$classes = str_replace( 'menu-item', 'menu-item current-menu-item', $classes );
				remove_filter( 'nav_menu_css_class', 'namespace_menu_classes', 10, 2 );
			}
		}
		return $classes;
	}