Hi,
Thank you for your feedback.
I've found that when used, the separator checkout view could lead in some cases to unwanted refresh loops following modifications to the checkout system to automatically go to the next step when the current step is empty in HikaShop 5.1.2.
I've made a hotfix on our end to properly handle the separator view that you're using on the address step of your checkout.
Download again the install package of HikaShop 5.1.2 on our website and install it on yours and it will add the patch to fix this.