Ok.. problem was due to the usage of a multi tenant system with FOP2 version 2.30.00 (old). The latest FOP2 Manager allows the selection of individual tenants to enable the service, so you can select which tenants will have access to the FOP2 service. That way you can use the standard license with no extra costs to give service for up to 5 tenants. sbasan had much more than 5 tenants, but not an extended license, and the Tenant selection in the newer FOP2 Manager works only with the updated autoconfiguration scripts in more recent FOP2 versions. By using an older FOP2 version, the previous autoconfiguration scripts just printed out all tenants, not only the selected ones from the FOP2 Manager, and reached the 5 tenant limit making some tenants unavailable.
So, if you use an older FOP2 with a multi tenant system and plan to use the tenant selection via the FOP2 Manager, then go ahead and upgrade everything: fop2 and the fop2 manager. If you upgrade only the fop2 manager you have the change of having features that won't work with the server, like this tenant selection.
In this particular case, updating just autoconfig-users.sh in his installation with the latest version fixed the issue.