I hope you are well. I'd suggest first clearing your browser's cache and cookies. If that doesn't help, then try using a cacheless browsing window (FireFox private window, Chrome incognito, etc.), then an entirely different browser.
If that also doesn't work, see if you can duplicate the issue on a different computer, such as a mobile device. Once you identify where the issue is, you can then look for a resolution.
The CName you are creating is essentially giving the subdomain, a subdomain. See the article below to create a subdomain in your DNS. In the meantime, change the www subdomain "Points to" field - on the CName record in your screenshot - to "@" (no quotes) and point it back to the primary domain.