Drilling Mode Glitch

I am trying to set up drills, but when there are fewer questions remaining than any of the number of question increment choices, I'm getting an error message for creating drills.

E.g. I have 4 questions left in the "Let Virtual Tutor Pick" logical reasoning section, but since the lowest increment of # of questions is 5, I get the following message: "Sorry, we were not able to create a drill based on your criteria. Please try again."

#help