PayPal Express Checkout - Problems when redirected to Woocommerce checkout

[NiallMcG]

hiya,

I can't figure out what's wrong after researching forums, tutorials, and other documentation online, so any help would be much appreciated.

When using Express Checkout and login into PayPal to make the payment, it redirects me to Woocommerce's checkout page. At the bottom of the page, the PayPal Express Checkout button appears but it doesn't work, that is, you can't click on it (screenshot attached), therefore you can't make the purchase. 

Thanks in advance for any help