Originally Posted by dnanian
Perhaps try reselecting the image in the "Disk Image..." pop-up (it'll be gray, select it anyway) and recreating the schedule?
Hmm... I had tried that a million times. I hopped out of the car and got back in again, and now it is working. The only thing that I did that was slightly different this time was that I also unmounted the SuperDuper volume, as well as disconnecting the QNAP connection itself. Deleting and re-creating the schedule seemed to resolve the problem.
Mystery of the world... I wish I knew what the problem was.