Ok. I think this is where a bit of ignorace on my part is evident. Why would I need to add my custom domain to Netlify if I’m pointing to my Netlify subdomain from Cloudflare?
Because you need to tell Netlify to listen for requests to that hostname and to serve your site.
Looking at your screenshot again, I suggest you have not correctly configured DNS records. The apex domain shouldn’t have a CNAME record with your Netlify subdomain as the value. It should have an A record with the Netlify load balancer IP or a flattened CNAME with the Netlify load balancer domain.