Hi all, been pulling my hair out trying to fix this after upgrading to 1.7.6.3 so figured I would ask here for some help!
The website in question is staging.myiconart.com and we're having problems with both login and the cart. Logging in either as a customer in FO or as an admin in BO just refreshes the login screen with the fields blank again; it doesn't seem to clock that the login has even taken place - no redirection, etc. A cookie is created but nothing changes. Likewise when you add something to the cart, the button does nothing and no products appear in the cart.
I've looked into this problem online and tried the solutions that have worked for others but clearing my cache/cookies hasn't helped, it's a consistent issue across every browser and device. Running on PHP 7.2 with all the necessary extensions and when I turn on debug mode there's no visible errors.
I'm aware that the product images aren't displaying but that's just an issue with the staging environment (images work properly in the live env; the image links aren't set to include the subdomain).
I'm sure I'm missing something obvious so any help would be much appreciated!