Not sure if I'm describing it correctly,
but we did a migration from another server where lets say;
site1.com was the main hosted account, which had addon1.com as a add-on domain which was just a shorter spelling of the main domain.
However now it's directing the add-on domain to the subdomain which actually just points to the public_html folder anyways.
So it's basically changing addon1.com to addon1.site1.com which is really just site1.com public_html folder anyways.
So it seems something got lost in the translation, the domain is functioning and resolving to the right spot, however it's just no longer properly "masking" it.
but we did a migration from another server where lets say;
site1.com was the main hosted account, which had addon1.com as a add-on domain which was just a shorter spelling of the main domain.
However now it's directing the add-on domain to the subdomain which actually just points to the public_html folder anyways.
So it's basically changing addon1.com to addon1.site1.com which is really just site1.com public_html folder anyways.
So it seems something got lost in the translation, the domain is functioning and resolving to the right spot, however it's just no longer properly "masking" it.