Custom Email Domain with iCloud+ Troubleshooting - User Does Not Exist Error

I own a domain that I currently use with Google Workspace for my family's email. I tried to move it over to Apple using the new iCloud+ with Custom Email Domain setup. I used the option to add it to my iCloud+ account for me and my family members, and we are already all part of a family group with Apple One.

Everything went smoothly, and iCloud accepted and verified our existing email addresses. I also successfully updated all of the DNS settings with my domain registrar. We each received our confirmation emails from Apple stating that our custom email addresses were ready, and they showed up in our respective iCloud.com accounts. They were also visible in the Apple Mail app on our iMac and iPhones.

Sending email from our addresses worked as expected, but they were unable to receive any emails. I tested sending inbound emails from several different external email addresses. In all cases, the emails bounced back as undeliverable. The Mail Delivery System error stated: "User does not exist"

There are further technical details in the error report, which I have left out for security reasons.

I tried both creating a new email to send to my custom domain on iCloud, and I also tried replying back to the emails that I successfully sent from my custom domain. In all cases, the inbound emails to my custom domain on iCloud bounced back as undeliverable with the same error, "User does not exist"

I called Apple Support, and the rep that I spoke with told me that there is a known technical bug on Apple's end that is causing this problem. She did not have any further info as far as when this might be resolved. I have been unable to find any information online mentioning this issue, and I'm wondering if anyone else has run into this problem?

In the meantime, I removed my domain from iCloud+, and I updated my DNS settings back to Google Workspace again. My emails are functioning normally again, as expected.