Hi!
Not sure whether it’s WP 4.7 or myself but I can’t solve the problem.

I’ve made a Piklist plugin. The plugin settings page was added to admin menu like this:

public function kd_admin_menu( $pages ) {

	// add settings page
	$pages[] = array(
		'page_title' => NULL, 
		'menu_title' => esc_attr__( 'Settings', 'kd' ), 
		'sub_menu' => 'edit.php?post_type=kd',
		'capability' => 'manage_options', 
		'menu_slug' => 'general_settings', 
		'setting' => 'general_settings', 
		'single_line' => true, 
		'default_tab' => esc_attr__( 'General settings', 'kd' ), 
		'save_text' => esc_attr__( 'Save Options', 'kd' )
	);

	return $pages;
	
}

Under my plugin folder I’ve created “/parts/workflows/” folder which is used to hold plugin settings across 4 tabs. It means that each file represents one tab + header file. Here they are:

— /parts/workflows/plugin-settings-header.php —

/*
Flow: Plugin Options
Page: edit.php, general_settings
Post Type: kd
Header: true
Position: title
*/

— /parts/workflows/plugin-settings-general.php —

/*
Title: Features Panel
Post Type: kd
Flow: Plugin Options
Setting: general_settings
Order: 10
*/

— /parts/workflows/plugin-settings-single-post.php —

/*
Title: Single Post
Post Type: kd
Flow: Plugin Options
Setting: general_settings
Order: 20
*/

— /parts/workflows/plugin-settings-archive.php —

/*
Title: Category
Post Type: kd
Flow: Plugin Options
Setting: general_settings
Order: 30
*/

— /parts/workflows/plugin-settings-rewrite-rules.php —

/*
Title: Rewrite Rules
Post Type: kd
Flow: Plugin Options
Setting: general_settings
Order: 40
*/

Of course, each of the files contains Piklist fields which I guess are irrelevant
in this case.

Everything looks right, tab switching works fine, however, when I hit Save Options button, I end up with the blank WordPress page saying:
ERROR: options page not found.

Is there anything wrong with workflow header?

Thanks for any clue!