What is the ph of the water you are using to mist them?
What is the Ph of the soil of the plant having problems?

Stop misting that plant. Each plant is a little different some like more nutrients then the one next to it. Even though they are from the same mother each plant can mature at a slightly different rate. That picture looks like either a Ph problem in the soil; the misting water or they just have problems dealing with the spray in their leaves and are baking from the inside out. There are many times when people mist their plants and the water droplets act like a magnifying glass and cook the inside of the plant. (It's like when kid's used the magnifying glass that came in cracker jacks to burn ants and leafs) same idea.

Pictures of your plants would be more helpful when you get them.

The rest is just an educated guess.