Here in Z6 my plants are in the greenhouse with 40 to 50* nights and 50-70* days. New leaves have just curled No insects visiable

I have had this (curled leaves) on many of my rooted cuttings and have been fighting Aphids with mine. Do have to be aware of Broad Mites which are not visible by the naked eye. They tend to be in the growth tip and can be difficult to get rid of. I break off the tip and garbage it.
With seeing the holes that you have in some of the leaves, leads me to think that it is an insect which created the holes.
I have found with some of the plants showing signs of the curled leaves that the leaves that merge later do not have this problem.
I spray mine before coming in for the winter months, but many times it is the Aphid eggs which hatch later one or have been in the soil. Usually a spray with insecticidal soap w a drop of Dawn dish soap in it, sprayed the first time and then again 3 days later.

I love Brugs, but am almost ready to ditch them because they are such horrible bug magnets. Mine are never bug free, despite almost daily soap sprays and I've even used the Bonide spray. They are the worst in my greenhouse for bugs.

Karen, I find that when they are in the house or an enclosed greenhouse that they are exactly that. Bug magnets. I have a bunch of cuttings and many seedling going this year in a room. Not going to keep them inside next winter. Atleast when they are old enough to go dormant or semi-dormant, there is not much of a concern w bugs.

I have leaf curl and cant see any mites upon inspection. But I will treat it.