i finally after about 4 hours of troubleshooting (i'm not a developer) got this working.
1) when opening the webpart properties in sharepoint designer i found the GUIDs of the list and datamapping references pointed to the wrong list altogether even though i'd selected them correctly using the UI. so i had to edit them by finding the guid of the correct list (using this method: http://nickgrattan.wordpress.com/2008/04/29/finding-the-id-guid-for-a-sharepoint-list/)
2) i had an example of a webpart that was put together correctly that i used as my template, and i edited it to replace the correct datamapping properties like so:
the ones i replaced were:
after i did that, and it STILL didn't work, i adjusted the "Title" field to show in my document set, and discovered that the Title field was not what i'd expected. I'd created the Document Set programattically using Sharepoint Designer Workflow and found out that the "Path and Name" property doesn't actually set the Title. The Title was being set to be the same Title as the originating workflow's list item.
so what i did to accomodate was change the filter value in the above block as you see:
this resulted finally in the query working. here's an image of the query on the left in the embedded document set instance - where the bold is the Name field (which matches the PALTitle field of the Initiation Items list) and the highlighted is the Title field that was created that matches the initiation item Title.