"This email address cannot be used as an Apple ID at this time." With new iCloud email.

I am in the process of switching my primary personal email from Gmail, which I used when I created my Apple ID, to iCloud. I created my iCloud email recently and I am trying to update my Apple ID to my iCloud email, but when I try to switch I receive an error that states:

"This email address cannot be used as an Apple ID at this time."

Is this because my iCloud email address is too new? Or could there be another issue?

Thanks!