Disabling LDAP - user logins fail

I have a RocketChat system that was closed down and needs to be accessible for archival purposes. So far not a problem, the system is running, I can access all the channels, though only with local accounts of either admin, or newly created. Problem is, most accounts were created through LDAP, and the former LDAP system isn’t available anymore, and accounts have been set up differently on the new infrastructure. I tried setting the “fallback” option the LDAP settings, but even when I set the local password new and use that PW, login fails. Same happens when I disable LDAP generally.

What am I missing here?