Print map imagery not visible when imagery file moved

I was trying to do some cleanup on my GIS server, which included testing moving the imagery files my cached image services are based on. Not surprisingly, my cached image services still work in my site since all of the tiles are stored in my AGS cache.

 

However, if I moved the original image files, then the imagery doesn't show up when I print a map or run a report with a feature map in my GVH.

 

Why would print imagery be dependent on where my original image files are stored if I'm using cached image services in my site?