diff --git src/wp-admin/js/customize-nav-menus.js src/wp-admin/js/customize-nav-menus.js
index 628ffa8..b4e7be5 100644
--- src/wp-admin/js/customize-nav-menus.js
+++ src/wp-admin/js/customize-nav-menus.js
@@ -1250,16 +1250,21 @@
 					return;
 				}
 
-				var titleEl = control.container.find( '.menu-item-title' );
+				var titleEl = control.container.find( '.menu-item-title' ),
+				    titleText = item.title || api.Menus.data.l10n.untitled;
+
+				if ( item._invalid ) {
+					titleText = api.Menus.data.l10n.invalidTitleTpl.replace( '%s', titleText );
+				}
 
 				// Don't update to an empty title.
 				if ( item.title ) {
 					titleEl
-						.text( item.title )
+						.text( titleText )
 						.removeClass( 'no-title' );
 				} else {
 					titleEl
-						.text( api.Menus.data.l10n.untitled )
+						.text( titleText )
 						.addClass( 'no-title' );
 				}
 			} );
@@ -1303,9 +1308,9 @@
 				'menu-item-edit-inactive'
 			];
 
-			if ( settingValue.invalid ) {
-				containerClasses.push( 'invalid' );
-				control.params.title = api.Menus.data.invalidTitleTpl.replace( '%s', control.params.title );
+			if ( settingValue._invalid ) {
+				containerClasses.push( 'menu-item-invalid' );
+				control.params.title = api.Menus.data.l10n.invalidTitleTpl.replace( '%s', control.params.title );
 			} else if ( 'draft' === settingValue.status ) {
 				containerClasses.push( 'pending' );
 				control.params.title = api.Menus.data.pendingTitleTpl.replace( '%s', control.params.title );
diff --git src/wp-includes/class-wp-customize-setting.php src/wp-includes/class-wp-customize-setting.php
index 01b84c8..65fa2e2 100644
--- src/wp-includes/class-wp-customize-setting.php
+++ src/wp-includes/class-wp-customize-setting.php
@@ -885,7 +885,7 @@ class WP_Customize_Nav_Menu_Item_Setting extends WP_Customize_Setting {
 		'status'           => 'publish',
 		'original_title'   => '',
 		'nav_menu_term_id' => 0, // This will be supplied as the $menu_id arg for wp_update_nav_menu_item().
-		// @todo also expose invalid?
+		'_invalid'         => false,
 	);
 
 	/**
@@ -1144,6 +1144,14 @@ class WP_Customize_Nav_Menu_Item_Setting extends WP_Customize_Setting {
 			}
 		}
 
+		if ( ! isset( $this->value['_invalid'] ) ) {
+			$this->value['_invalid'] = (
+				( 'post_type' === $this->value['type'] && ! post_type_exists( $this->value['object'] ) )
+				||
+				( 'taxonomy' === $this->value['type'] && ! taxonomy_exists( $this->value['object'] ) )
+			);
+		}
+
 		// Remove remaining properties available on a setup nav_menu_item post object which aren't relevant to the setting value.
 		$irrelevant_properties = array(
 			'ID',
@@ -1246,6 +1254,8 @@ class WP_Customize_Nav_Menu_Item_Setting extends WP_Customize_Setting {
 		$should_remove = (
 			false === $this_item
 			||
+			true === $this_item['_invalid']
+			||
 			(
 				$this->original_nav_menu_term_id === $menu->term_id
 				&&
@@ -1417,6 +1427,7 @@ class WP_Customize_Nav_Menu_Item_Setting extends WP_Customize_Setting {
 			'status'           => 'publish',
 			'original_title'   => '',
 			'nav_menu_term_id' => 0,
+			'_invalid'         => false,
 		);
 		$menu_item_value = array_merge( $default, $menu_item_value );
 		$menu_item_value = wp_array_slice_assoc( $menu_item_value, array_keys( $default ) );
@@ -1449,6 +1460,8 @@ class WP_Customize_Nav_Menu_Item_Setting extends WP_Customize_Setting {
 			$menu_item_value['status'] = 'publish';
 		}
 
+		$menu_item_value['_invalid'] = (bool) $menu_item_value['_invalid'];
+
 		/** This filter is documented in wp-includes/class-wp-customize-setting.php */
 		return apply_filters( "customize_sanitize_{$this->id}", $menu_item_value, $this );
 	}
diff --git tests/phpunit/tests/customize/nav-menu-item-setting.php tests/phpunit/tests/customize/nav-menu-item-setting.php
index ad2e7d2..367d947 100644
--- tests/phpunit/tests/customize/nav-menu-item-setting.php
+++ tests/phpunit/tests/customize/nav-menu-item-setting.php
@@ -92,6 +92,7 @@ class Test_WP_Customize_Nav_Menu_Item_Setting extends WP_UnitTestCase {
 			'status' => 'publish',
 			'original_title' => '',
 			'nav_menu_term_id' => 0,
+			'_invalid' => false,
 		);
 		$this->assertEquals( $default, $setting->default );
 
@@ -458,6 +459,7 @@ class Test_WP_Customize_Nav_Menu_Item_Setting extends WP_UnitTestCase {
 			'status' => 'forbidden',
 			'original_title' => 'Hi<script>alert(1)</script>',
 			'nav_menu_term_id' => 'heilo',
+			'_invalid' => false,
 		);
 
 		$sanitized = $setting->sanitize( $unsanitized );
@@ -664,4 +666,47 @@ class Test_WP_Customize_Nav_Menu_Item_Setting extends WP_UnitTestCase {
 		$this->assertEquals( 'deleted', $update_result['status'] );
 	}
 
+	/**
+	 * @ticket 33665
+	 */
+	function test_invalid_nav_menu_item() {
+		$menu_id = wp_create_nav_menu( 'Primary' );
+		register_post_type( 'poem', array(
+			'public' => true,
+		) );
+
+		$post_id = self::factory()->post->create( array( 'post_type' => 'poem', 'post_title' => 'Code is poetry.' ) );
+		$post = get_post( $post_id );
+		$item_id = wp_update_nav_menu_item( $menu_id, 0, array(
+			'menu-item-type' => 'post_type',
+			'menu-item-object' => 'poem',
+			'menu-item-object-id' => $post_id,
+			'menu-item-title' => $post->post_title,
+			'menu-item-status' => 'publish',
+			'menu-item-position' => 1,
+		) );
+		$setting_id = "nav_menu_item[$item_id]";
+
+		do_action( 'customize_register', $this->wp_customize );
+		$setting = $this->wp_customize->get_setting( $setting_id );
+		$this->assertNotEmpty( $setting );
+		$value = $setting->value();
+		$this->assertFalse( $value['_invalid'] );
+		$value_object = $setting->value_as_wp_post_nav_menu_item();
+		$this->assertFalse( $value_object->_invalid );
+
+		$setting = new WP_Customize_Nav_Menu_Item_Setting( $this->wp_customize, $setting_id );
+		$value = $setting->value();
+		$this->assertFalse( $value['_invalid'] );
+		$value_object = $setting->value_as_wp_post_nav_menu_item();
+		$this->assertFalse( $value_object->_invalid );
+
+		_unregister_post_type( 'poem' );
+		$setting = new WP_Customize_Nav_Menu_Item_Setting( $this->wp_customize, $setting_id );
+		$value = $setting->value();
+		$this->assertTrue( $value['_invalid'] );
+		$value_object = $setting->value_as_wp_post_nav_menu_item();
+		$this->assertTrue( $value_object->_invalid );
+	}
+
 }