WP Smush Pro unable to update, blank screen

Anyone having the same issue we're experiencing?
When trying to update WP Smush Pro from the network plugins panel, we are redirected to a blank screen. Also, when trying to update from within the WPMU control panel from within the site, the same result is seen.
We are redirected to the following url, where the blank screen surprised us:
http://s2mobiel.nl/wp-admin/network/update.php?action=upgrade-plugin&plugin=wp-smush-pro%2Fwp-smush.php&_wpnonce=4696ffbbe3

I dearly hope someone could assist us timely with this issue, we have an important licensing deal coming up and we urgently want to have our platform in tip-top shape!

Thanks!