Engage files loosing links

Hello,

I am working on an project in Studio 13 and have multiple embedded Engage and Quizmaker files.  I am working off of my C: drive and have kept all of the files in the same folder.  At certain times all of the embedded files seem to lose their links to the Engage and Quizmaker files.  If I go into the file by clicking on the "Edit Engage/Quizmaker" button in powerpoint, the file will open and I can make my changes.  I then hit "Save and Return to Presenter" and once the file closes I can see in powerpoint that it was updated; however, it saves that file in a place (which I cannot find) and does not update the Engage or Quizmaker file that is sitting in the folder where I have the project saved.  If I delete the Engage or Quizmaker file from powerpoint and re-link import the existing file from the project folder I can make a change and it will save to the copy in the project folder; however, I have to delete and re-import the files every time I want to make a change. 

Any help would be much appreciated.

Thanks!