Lost ability to add new ISOLATED sites to existing users

Within the last year I learned how to isolate sites with their own SFTP using these links: https://bensmann.no/restrict-sftp-users-to-home-folder/ https://freek.dev/411-let-your-clients-use-sftp-on-a-forge-provisioned-server

Clients happy, I'm happy. But now one of the clients is asking me to add a new site, but I am running into an error on Forge if I try to add an isolated site to any of the current users I am using for isolated directories: "We were unable to add a site to your server (mindful-creative)."

My SSHD_CONFIG file looks like this: Subsystem sftp internal-sftp Match User brian,ftptest,repelbwp ChrootDirectory %h ForceCommand internal-sftp X11Forwarding no AllowTcpForwarding no PasswordAuthentication no

What should I check to try to get this fixed?