Fatal error: Using $this when not in object context in /data/web/virtuals/12507/virtual/www/libraries/joomla/plugin/plugin.php on line 102
I saw few more users had the same problem, but no response on AUP forum.
I had no problem with older version, but now, I don't recommend this plugin!!!
Please, update with latest version to fix issue with sync users. Problem solved from 1.7.2.