Hey @IronStrikesIron. Thanks for reaching out. I appreciate the context that you have shared with us as that is very helpful! Do you happen to see that this custom domain is listed when you navigate to Settings > Domains, by any chance? If you happen to see any error messages when you navigate to the domain section in the settings - let me know as that would be very useful to understand what may be causing the issue. Looking forward to your response.
Ollie | Social Care @ Shopify - Was my reply helpful? Click Like to let me know! - Was your question answered? Mark it as an Accepted Solution - To learn more visit the Shopify Help Center or the Shopify Blog