i dont have the fan blowing directly at any plant its more so blowing across the damp towel and up towards the lights, and i have a pc fan sucking the hot air from the lights up towards the main exhaust for the box.what type of air circulation other then the fan that is blowing over the towel you are using?
how strong is the fan blowing on that side of the plant with the curled leaves?
I'd almost say it looks like high temps, the low humidity may just be accelerating the issue.
Could be the amount of wind applyed to the leaves causing them to dry out.
Are the leaves brittle or are they still fleshy?