I've been tasked with connecting our production org (via SSO) to several other orgs, all of which are sandboxes unrelated to our production org. To achieve the requirement I followed the below documentation to configure the new functionality. I tried the documentation with a dev org and with a sandbox org, but both failed to communicate with our prod org for SSO.
Implementing Single-Sign-On Across Multiple Organizations
Because I need to SSO into sandbox orgs we have been unable to use the Environment Hub feature of Salesforce. Have I missed something or is the documentation I'm following missing something? If so, what? Has anyone else managed to get SSO working using this documentation?