I've been having this problem intermittently but now I've got a game where my dupes simply won't work. They constantly go into a repeating animation where they stand there and don't do anything. I've moved them back and forth but they won't do any of the things I've queued. It looks like they are trying to pick something up over and over again. I've attached a save file where all three of my dupes do it every time the game loads.
Load the save file and unpause it. Two of the dupes will immediately start picking up nothing and the third will do so immediately after finishing his dig order.