I contacted Shopify Plus support. They pushed out a fix for this last night which appears to have resolved the issue

We have a similar setup. Instead of password protecting the store, we have added some javascript inside of the main theme.liquid file which immediately redirects users to our custom storefront. This theme file is not loaded when viewing checkout so i...

I am creating a cart using the Storefront API: https://shopify.dev/docs/api/storefront/2024-01/mutations/cartCreate I have a headless store though I would like to leverage the cart and checkout functionality from shopify. I see the cart has a field c...