When consuming SOAP APIs, Service Studio can't easily handle a WSDL with a "List" element directly inside another "List" element.
Currently, the workaround for this is to add a dummy attribute to the parent list, to force Service Studio to generate a Structure with a List Attribute.
For example, this XML structure can't be handled by Service Studio, but...:

... this structure can ("ParentList" Structure will have a "dummy" attribute and a "ChildList" attribute):

Would be nice if the first case could be natively handled by Service Studio without resorting to this hack.