Index: src/wp-admin/includes/class-wp-list-table.php
===================================================================
--- src/wp-admin/includes/class-wp-list-table.php	(revision 32720)
+++ src/wp-admin/includes/class-wp-list-table.php	(working copy)
@@ -850,8 +850,13 @@
 	 * @return array
 	 */
 	protected function get_column_info() {
-		if ( isset( $this->_column_headers ) && is_array( $this->_column_headers ) && count( $this->_column_headers ) >= 4 ) {
-			return $this->_column_headers;
+		if ( isset( $this->_column_headers ) && is_array( $this->_column_headers ) ) {
+			$column_headers = array( array(), array(), array(), null );
+			foreach ( $this->_column_headers as $key => $value ) {
+				$column_headers[ $key ] = $value;
+			}
+
+			return $column_headers;
 		}
 
 		$columns = get_column_headers( $this->screen );