Apex domains cannot have CNAME records.
Question and response
Question
dig spf.nice.com. NS
Answer
spf.nice.com. 5 NS ns-1756.awsdns-27.co.uk.
spf.nice.com. 5 NS ns-213.awsdns-26.com.
spf.nice.com. 5 NS ns-529.awsdns-02.net.
spf.nice.com. 5 NS ns-1061.awsdns-04.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0