Apex domains cannot have CNAME records.
Question and response
Question
dig adaptavist.cloud. NS
Answer
adaptavist.cloud. 5 NS ns-1771.awsdns-29.co.uk.
adaptavist.cloud. 5 NS ns-714.awsdns-25.net.
adaptavist.cloud. 5 NS ns-34.awsdns-04.com.
adaptavist.cloud. 5 NS ns-1102.awsdns-09.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0