Unable to set workspace custom name to match existing subdomain

Hello,

There appears to be a feature in Hub Business for setting a custom workspace name, which would then be used instead of the default URL https://ca.devolutions.app/<GUID>.

When attempting to set this to match the existing subdomain configured, the set button does not enable. For example, if hub url/subdomain is already CompanyABC.devolutions.app, the workspace url cannot be set to https://ca.devolutions.app/CompanyABC

Also wondering why there is both a custom subdomain https://CompanyABC.devolutions.app and a custom workspace name https://ca.devolutions.app/CompanyABC, and how they would be utilized differently.

Please let me know if you would like any additional info.
Thanks
Joe