In MODx 0.9.5 rev 1751 (beta 5), /manager/frames/tree.php use short PHP opening tag <? on lines 386, 389, 399,399, 432 instead of the preferred <?php. As a result, for installations that have short_open_tag turned off, the documents tree isn’t display. So, if you have
this version you can modify the code or change your PHP.INI