We face a strange error in the checkout on the domain.com/checkout/#payment page, when clicking the place order button.
For some reason in some cases, we still can't find when exactly, the customer on checkout when clicking the place order button receive the error:
The shipping method is missing. Select the shipping method and try again.
But we only have 1 active shipping method, the default "Flat Rate" method and is always select because it's the only value. And this issue can be solved by the customer, by moving back to the shipping step (domain.com/checkout/#shipping) and without any change directly go back to the payment step. Then clicking the place order button and it works perfectly.
We use a Cart Price Rule for free shipping, when the cart amount is above $50. Then the customer receive free shipping, otherwise the default Flate Rate is calculated.
Any idea what can cause this issue and how we can solve this? We run Magento 2.4.4, but we had this issue also on 2.4.3