PayPal Express not redirecting back to Craft Commerce
What's the output in your templates of:

{{ craft.config.tokenParam }}


If it isn't t suspect your config is not setting the tokenParam for some reason.

Can you test with a stripped out general.php with only hard-coded values (No multi-environment config, or if($_SERVER ... checks) 

return array(
    'tokenParam' =&gt; 'myCraftToken'
    // ..other hard coded settings
);