PayPal creates a second account for just-registered customers, changes shipping to free

[jc666]

I'm having an issue, or a couple rather: I'm testing checkout and payment on a new shop and whenever I go through the checkout process, after registering or logging in and selecting payment method (PayPal is the only one I've made available), going to the PayPal login and payment confirmation, instead of completing the checkout process, takes you back to the cart, logged in with a new account that is using the information from PayPal, logging you out of the account you just created on the site, rendering the registration process on the site completely useless (on the back office you can see both the account created during checkout and the new account using the PayPal information). 

 

And as if that wasn't enough, every time it takes you back to your cart to select a new shipping method with the new PayPal-created account, all shipping options are changed to free shipping, regardless of zones, products, or handling charges.

 

I've tried different accounts, addresses, shipping methods, updating weight, costs, zones, and nothing works.

 

tl;dr: PayPal checkout logs you out of your account, creates a new one automatically and changes all shipping options to free shipping.

 

Any leads or help will be greatly appreciated, I've run into so many issues during this past month setting this shop it's unbelievable.... this feels like the last step to having a functional shop, but there is no indication on how to fix this anywhere... Thanks.