Why does media go offline in Audition?

Each time I save files in the Multitrack the files return Offline. The strange thing is I can see the files clearly in the Audition program. The particular files I'm working with come from an external hard drive, but I transferred them to my local drive before starting the project. Also, I noticed that I've only been having this issue after the recent update. Could that be the culprit? Really need help because this is affecting the speed I can get projects done. 

[Mod note - put into a thread of its own to prevent version confusion]