Today I was printing a four color project across two AMSs. Heard the printer trying to load reload load over and over. Went in there to see why and the second AMS was blinking red.
Checked the screen on the printer. It said possible AMS data cable problem. Reseated both ends same error. Since i had three spares from the purchase of the second AMS, i swapped out the cable and she was good to go.
Never heard of a cable going bad during a print. Usually its after you mess with the cable.
One thing that was confusing, on the AMS screen, I had to click on a grey retry button. No where did it say to click on that. I just clicked one time and off she went to printing. It never changed color or state. 
Happy ending for me. Saved the print also.