Unable to create custom target systems

Until last month we could create any custom target system we liked. But now, when we try to create a custom target system I get this error:

[1025012] Object (test (test)) could not be saved!
[810306] Error during execution of 'OnSaving' in logic module 'TSB.Customizer.UNSRootB'.
[2088383] The system configuration does not allow you to add or remove objects of type 'Custom target systems'.

 

I checked the confguration parameter TargetSystem\UNS\CreateNewRoot but it is Enabled and set to 1 as are of course the levels above.

 

I have no idea where to start looking for an solution.

Has anyone seen this before, and more important, does anyone know how to solve this?