Index: src/wp-includes/formatting.php
===================================================================
--- src/wp-includes/formatting.php	(revision 45881)
+++ src/wp-includes/formatting.php	(working copy)
@@ -2270,6 +2270,33 @@
 				'%cc%80',
 				'%cc%84',
 				'%cc%8c',
+				// non-visible characters
+				'%e2%80%80',
+				'%e2%80%81',
+				'%e2%80%82',
+				'%e2%80%83',
+				'%e2%80%84',
+				'%e2%80%85',
+				'%e2%80%86',
+				'%e2%80%87',
+				'%e2%80%88',
+				'%e2%80%89',
+				'%e2%80%8a',
+				'%e2%80%8b',
+				'%e2%80%8c',
+				'%e2%80%8d',
+				'%e2%80%8e',
+				'%e2%80%8f',
+				'%e2%80%a8',
+				'%e2%80%a9',
+				'%e2%80%aa',
+				'%e2%80%ab',
+				'%e2%80%ac',
+				'%e2%80%ad',
+				'%e2%80%ae',
+				'%e2%80%af',
+				'%e2%80%9f',
+				'%ef%bb%bf',
 			),
 			'',
 			$title
Index: tests/phpunit/tests/formatting/SanitizeTitleWithDashes.php
===================================================================
--- tests/phpunit/tests/formatting/SanitizeTitleWithDashes.php	(revision 45881)
+++ tests/phpunit/tests/formatting/SanitizeTitleWithDashes.php	(working copy)
@@ -140,4 +140,12 @@
 		$this->assertEquals( 'aaaa', sanitize_title_with_dashes( 'ááa´aˊ', '', 'save' ) );
 	}
 
+	/**
+	 * @ticket 47912
+	 */
+	function test_replaces_non_visible_chars() {
+		// Non visible characters are included in the text.
+		$this->assertEquals( 'abcd', sanitize_title_with_dashes( 'a b 	c d', '', 'save' ) );
+	}
+
 }