"Hide My Email" reply exposes personal iCloud email address instead

When I receive an email to one of my Hide My Email addresses and then reply in Apple Mail on macOS it shows that the email will come from the Hide My Email address, so it appears to work, HOWEVER once I click send and look at the email in the sent mail it shows that it was sent from my primary iCloud email address instead.

This has been a consistent issue and (and others) have noticed for years, and I've never seen anyone post an actual solution to it.

Has anyone found a way to reply to an email sent to your Hide My Email address and have it continue to hide your address behind the proxy address? That's how Apple says it is supposed to work in their documentation, however it doesn't.