This solution was created while 6.x was current...
Concerning this issue...Please have a look at the NMSP 6.x user guide notes on page 234. Or search for "word template" for "newer" versions of NMSP User Guide.
After you review the details discussed on page 234...and attempt this procedure, the below information may come in handy too.
When we create a Word document, we allow you to specify a template. I believe that there isn't really a difference between a "docx" and a "dotx" (a template). If this is true, then one trick is to use "Save to Intermediate File" and tell it to save attachments in a separate folder. This way the generated Word documents will end up in their own folder.