Apex domains cannot have CNAME records.
Question and response
Question
dig myswimplatform.com. NS
Answer
myswimplatform.com. 5 NS ns-725.awsdns-26.net.
myswimplatform.com. 5 NS ns-1242.awsdns-27.org.
myswimplatform.com. 5 NS ns-1033.awsdns-01.org.
myswimplatform.com. 5 NS ns-2024.awsdns-61.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0