Broken join for W3TC (WTCPM) from https://wordpress.org/support/topic/broken-join-for-w3tc-wtcpm/

folders-broken-join-for-W3TC.patch

diff --git a/includes/folders.class.php b/includes/folders.class.php
index ff6fc72..a3d23ad 100644
--- a/includes/folders.class.php
+++ b/includes/folders.class.php
@@ -4979,7 +4979,7 @@ class WCP_Folders
                         AND ELPM.meta_key = '_elementor_is_screenshot') ";
         }
         if(defined("W3TC")) {
-            $join .= "LEFT JOIN ".$wpdb->postmeta." AS WTCPM
+            $join .= " LEFT JOIN ".$wpdb->postmeta." AS WTCPM
                 ON ( P.ID = WTCPM.post_id
                 AND WTCPM.meta_key = 'w3tc_imageservice_file' )";
         }