Rose, one quick observation .. most probably not related with our new feature but in general with multistep checkout behaviour.
I can not capture it as I should make a video not a screenshots, but I believe you will notice issue very easily. 🙂
Please go to my site from mobile (on desktop it is the same but less annoying 🙂 and add something to the cart.
Go to checkout, scroll to the end of “billing data” form, click on “Wybierz dostawę” which should direct you to “Delivery methods”.
Before you touch the screen, please notice what you got on the screen … you are not at the top of list of deliveries but somewhere in the middle of the page.
Same thing happens when you go next step (“Forma Płatności” = “payment”) and scroll down to the end of payments form and click “Wstecz” (“go back”)
All is ok if you are not scrolling the page.
The same happens on “separated” or “multistep” layouts.
Most probably this could be easily corrected if all of those buttons would direct to the hook placed just above the breadcrumbs with “checkout steps” 🙂 only content below could reload 🙂
shall you not be able to see what the issue is, I will try to somehow record my screen and provide a short video 🙂