Index: src/wp-includes/class-wp-list-util.php
===================================================================
--- src/wp-includes/class-wp-list-util.php	(revision 47766)
+++ src/wp-includes/class-wp-list-util.php	(working copy)
@@ -102,12 +102,23 @@
 		$filtered = array();
 
 		foreach ( $this->output as $key => $obj ) {
-			$to_match = (array) $obj;
+			$matched = 0;
 
-			$matched = 0;
 			foreach ( $args as $m_key => $m_value ) {
-				if ( array_key_exists( $m_key, $to_match ) && $m_value == $to_match[ $m_key ] ) {
-					$matched++;
+
+				if ( is_array( $obj ) ) {
+
+					// Treat object as an array
+					if ( array_key_exists( $m_key, $obj ) && ( $m_value == $obj[ $m_key ] ) ) {
+						$matched++;
+					}
+
+				} elseif ( is_object( $obj ) ) {
+
+					// Treat object as an object
+					if ( isset( $obj->{$m_key} ) && ( $m_value == $obj->{$m_key} ) ) {
+						$matched++;
+					}
 				}
 			}