If oil well is disabled while dupe is releasing backpressure, dupe remains stuck at oil well and will not complete the errand or abandon it. When oil well is enabled, dupe returns to normal behavior and continues errand.
Same issue here, at 3840x2160. It started when I went to build a ladder, includes cursor focal point duplication as well. Moves around screeen as I move, persistent across savegame as well.