(ERROR @ /var/www/html/modx/core/xpdo/xpdo.class.php : 2414) PHP warning: json_encode() [function.json-encode]: recursion detected

I have that same mixture, and some are blank.

As long as none of them contain anything else, the problem is not corrupted properties.

Have you tried upgrading to the same version? If you change your settings_version System Setting to an earlier version, you can "Upgrade" to the version you already have with UpgradeMODX. That will download all new MODX files, run setup, and clear the cache.

You might also try visiting the Manager with your browser in private or incognito mode if you haven't already, that will rule out the possibility of some old code stuck in the Browser's JavaScript cache.