Masked Subdomain Forwarding does not work if Squarespace is the registrar

Do not use Squarespace as your registrar if you wish to use a masked subdomain such as ours.

We transferred our primary domain from Dotster to Squarespace and based on what I read, I expected everything to work as before once the transfer was complete. I made sure our domain was working after the transfer and forgot about it. A few days later, we were starting to wonder why bookings were slowing down when a prospective customer messaged to tell us the "Save the Date" button on our primary website (which points to the subdomain) was no longer working.

So once I realized that the subdomain did not transfer, I put it back using the interface in Squarespace.  Forwarding works fine but the problem is in the displayed URL ... people see this extended URL (pictured) instead of our subdomain, so they no longer believe our site is secure and leave without booking.

This is costing us bookings, hours of wasted time, and it may be causing damage to our reputation as a scrupulously honest business that we've assiduously built for nearly 20 years.

When I asked about the issue via online chat, the agent finally acknowledged that masked domain forwarding is not available after sending me to online procedures for domain forwarding and subdomain pointers. I am told it's because "their registrar is set up differently" and the issue will be "reported to development," in other words, our only recourse is to move our domains to another registrar.

There is much to love about our Squarespace site, but this experience has been terrible.