Hi,
@Enc :
Please open a new thread for your issue along with a link to the shop and precise instructions to reproduce the issue so that we can reproduce the issue on your website and analyze what's going on.
@marcusadamski :
However, would it be possible to simply select the first available shipping method in the list, when in the checkout the customer presses the "registration" / "next" button - to confirm the contact / address details. At that point, the shipping methods are filtered and displayed, so the first shipping method just needs to be automatically selected.
So what you want is to reset the shipping method selection after using the registration/next button (since the shipping method is already selected before the first time the cart is loaded).
That's possible with the development of a custom plugin to add that process after the registration/guest form is processed.
While the solution I proposed is a bit convoluted, it doesn't require any coding. My goal was to provide you with a solution you can put in place right now, without having to code anything.