When using Test Authentication Agent Settings > Check User feature, the returned user is a service username instead of proper LDAP user, even if LDAP user is logged on and using that workstation at the same moment.
The above condition is being triggered if the PC launches any update services that might have been installed by for example A/V software like Sophos or NVidia drivers update processes on their own username causing the PC/Terminal Server to appear to have multiple users logged in simultaneously.
To verify this is the case, run a SSO test against the problematic machine's IP address, like in the screenshot below:
This condition can be resolved by adding the returned service username (in this example "UpdatusUser" - please note: usernames are case sensitive) under SSO user settings to bypass the returned query and resolve the actual user - this sometimes needs to be repeated if the returned username is still not the LDAP user, as some machines might have multiple update services installed. You can also use wildcards in case the usernames are not unified in the network, but repeating some part (f.e. UPDAT* will bypass all users whose name contains the "UPDAT" string followed by any other characters).
See Also: