Did you try running the Cron Job with PHP instead of WGET?
Besides that, I'm not sure if you tried this solution yet but if you haven't, feel free to give it a try.
Open up the cron.php file in your Magento root directory (usually "public_html") and look for the following line of codes:-
$isShellDisabled = (stripos(PHP_OS, ‘win’) === false) ? $isShellDisabled : true;
Add the following codes in a new line exactly after the above line of codes:-
$isShellDisabled = true;