What can be killing some of my jasmine plants? They do not get "direct sunlight"(heat), and are not over watered.?

Most jasmine species want full sun to partial sun. If they are getting NO direct sun, that could be part of the problem.

But you are giving us no description of what is happening other than the fact that they aren't doing well. It's a little like saying "I'm dying. Why?". It could be too much water, too little water, not enough sun, fungal problems, insect problems, or disease.

I would start by giving the poor thing a few hours of direct sun a day.