Gynura/velvet plant

I have always had a velvet plant/gynura. A few months ago it was getting leggy so I took some cuttings and stuck them in water to root. They were doing great until suddenly one day leaves stared dying.

It would start with a tiny "see thru" hole in the leaf and quickly take over the whole leaf leaving just the webbing. I cut off all infected leaves, and watched for more damage. If a leaf developed a hole all or part of it was cut off. I have seen no new damage in a week or better. I am left with 3 - 8-12" cuttings with only 3 to 5 leaves on top. I am going to re-cut then down to 5 or 6 inches and will try again.

Can anyone give me an idea of what attacked the plant?