At the checkout the built-in link "What is PayPal" opens an EMPTY pop-up window. Why? This is bad for customers as the link is supposed to gain their confidence. Using IE11 the window shows the default Magento 404 page but is completely blank using Firefox and Chrome.
Config: Magento 2.1.0
Theme: Luma (default, no theme or script editing)
PayPal Website Payments Standard
How can this be fixed please?