Redirection to membership details not working

Hello,

the redirection to the membership details after registration stopped working, perhaps after the plugin update (I'm not sure).

Before, I used to select a plan here http://slator.com/register/ then filled the registration form and I was automatically redirected to the membership details were I was able to choose the payment gateway.
Now, after the registration form I'm redirected to the Memberships page that shows all the plans http://slator.com/memberships/
What might be happening?

I granted support access.

Thanks for your help.