Concurrent Request generates PDF through BI Publisher when submitted directly, but not when spawned

Here's my issue.  I have created a concurrent request which uses BI Publisher to generate a .pdf file which is a copy of an invoice.  This process has been working very well.  We'll call it "XX Invoice PDF" for now.

However, I now have a need to have "XX Invoice PDF" submitted from inside another concurrent request (call it "XX Invoice Master Process") through FND_REQUEST.SUBMIT_REQUEST.   When I do this, and click "View Output" on "XX Invoice PDF", I see only the raw XML generated by the request, not the PDF file I was expecting.

As I said, if I submit "XX Invoice PDF" directly from the concurrent manager screen, it produces the PDF with no problem.  It is only when it is spawned from "XX Invoice Master Process" that it fails to produce the PDF and instead gives me just raw XML.