No new addons, even with all addons disabled the Donate button simply won't action. It won't load anything on click. Only changes are upgraded PHP 5.4.45 (from 5.3) and Xenforo upgraded to 1.5.7 (from 1.5.6).
Since upgrading to 1.5.7 the donate button doesn't work anymore. I've upgraded this addon as well, nothing. Any ideas? All templates are reverted, the paypal settings are still all the same.