Is this view right?
It looks like two things are going on here:
You (or someone) has configured the Argomenti Figli relation view to show entities from two related databases (Argomenti Figli AND Riferimenti Libri).
The smart folder is configured to show Argomenti Figli as the top level (with recursion enabled) and Riferimenti a Siti and Riferimenti Libri as levels below.
These configurations are independent of each other.
The configuration of the smart folder
Just to check - there is no bug, right?
The entity view relation fields are displaying as expected, and the smart folders are showing as expected…right?
The view configuration was wrong. all ok,