An Azure service that enables hosting Domain Name System (DNS) domains in Azure.
I would first check whether the CNAME is actually visible from public DNS. One hour is not necessarily a problem, especially if DNS caching is involved. Also, make sure the CNAME name and value match exactly what SendGrid provided. With Azure DNS, be careful not to add kec.ac.ke again if Azure is already appending the zone name.
If the record is visible through an external DNS lookup but SendGrid still cannot verify it, then the issue is likely with the record value or SendGrid's verification rather than Azure DNS itself.