Rule Designer - Compare a reference to a SmartObject value

Hello,

Does anyone has issue to make simple comparison between values from a Reference and a External SmartObject:

Here we return the entire collection from the List method.

But in the same way the result is False even if whenwe output each element they are there:

Lookup IDENTITY List of PO_NUMBER = PX0000 PZ0000
Contains true/false = False

I read the documentation concerning Rule Designer but there is only comparison between a Reference and a static text field.

I don't know if we are missing something .. this seems very wierd.

Do any of you encountered similar issue ? Is there a trick to be able to compare two objects like that ?

Thanks in advance,

Best Regards,