Pinpoint E-mail Campaign Does Not Deliver to Verified Identity Domain

I have set up an identity domain plus email address to support@[my-domain-name].com for a Pinpoint email channel campaign.

The segment includes a target email that uses the same domain, i.e., online@[my-domain-name].com, but that account does not receive the email in the inbox or spam folder. I do not have that issue with any other domain names in the segment.

My email is via exchange server hosted by Intermedia.

I reviewed the DNS records to make sure they are correct according to the host and AWS

Any ideas?