Well, If I remember correctly, it happened on the second or the third level after the "time shot" was introduced. The box was in the bottom left corner. Hope it helps and good luck!
There should not be any problems now. I fixed the boxes dragging bug and the multiple dragging. I think you can enjoy the game to the end.
If you still manage to find some bug feel free to message me.
P.S. I don't sleep so don't worry xD
