CNAME not working with <site>.pages.dev

I have setup a new PAGES site: dogs.aidraw.ai, this is a simple index.html file and I have a CNAME setup which points to: dogs-aidraw.pages.dev. When I access the site via the CNAME I get a blank screen, but when I access the site via dogs-aidraw.pages.dev it renders correctly. Can you help to let me know what the issue is here? Thanks,

Don’t add a CNAME yourself; you need to add the domain to the Pages project under “Custom Domains”. This will add the DNS entry for you.