CNAME records are not compatible with many other DNS record types. It is common practice to place them on the www subdomain instead, then forward the main domian there:
How do I create a CNAME?
A CNAME record is short-hand for Canonical Name record, which allows you to assign a domain or subdomain to another address or hostname. CNAME records should only be used if you can't use an A record.
NOTE: If you already have an A record within the Domain records section, please SKIP step 5!
Select "My Domains" from the left-side menu bar and click "Manage Domains" in the drop-down.
Check the box next to the domain name(s) and select "DNS Settings" from the "Action" drop-down menu.
On the new page, select the "Dynadot DNS" option from the drop-down menu.
In the "Domain Record (optional)" section at the top, select "Forward" as the record type, choose forward type, and enter "https://www.yourdomainname.ext" as the "Target Host". (NOTE: This is optional and please replace the value based on your own domain name.)
Under the "Subdomain Record (optional)" field, enter "www" as the subdomain, select "CNAME" as the record type and enter the CNAME record given to you.
Scroll down to the bottom of the page and click on the "Save Settings" button to save your changes.