So a couple of things to note that I should have included originally:
I have a working DKIM record for “domain.com” That is currently set to google apps domain and it is a TXT record. I am trying to set up a subdomain, “test.domain.com” on an Apple iCloud+ and it uses the CNAME approach above. I don’t know if I need to modify the initial DKIM record to allow the subdomain? Maybe that is the issue?
This is my first time setting up a separate email subdomain.