Engage Source Files - Where are they?

Hi -

I'm an experienced Articulate Presenter Studio '13 user but I recently ran into a problem with my Engage files.

1. I created a training module in PowerPoint.

2.  I added several Engage activities by opening Engage and using "New Interaction" and saved to my c:\Published folder.  Then I added the interaction via Articulate ribbon by clicking on Engage Interaction and clicking on "Add Existing".

Here is my problem:

Initially, when I needed to edit my Engage activity, I opened Engage and opened the interaction.  When I saved the file, it updated in  c:\published folder (showed date modified)

Yesterday, I opened the interaction within the PowerPoint slide using "Edit in Engage", modified the content and clicked on "Save and Return to Presenter".  However, when I looked at my Engage source files in c:\published folder, they did not show the "date modified" nor was the content updated.  When I looked at the Engage slide in my PowerPoint file, I saw "Last Modified: oct 16...".  

I did a search on my hard drive and my network drives and CANNOT find the .intr files updated in Presenter (only the file I updated in Engage).

I need my source files.

Question:

Where does Articulate store the file when modified within the PowerPoint/Presenter?

Note:  I work in a large corporation that uses networked drives.  I do NOT work on my projects on the networked drives, but rather on my hard drive to avoid problems like this in Articulate which does not appear to play well on networked drives.

Thank you for your help