I would say your problem probably has a bit to do with the miracle grow nutrients, these are not designed for the specific needs of weed plants. Since you are in flower now you should be transitioning into some kind of bloom food from the grow food, instead you are using the same n-p-k ratio throughout the plants entire life cycle which is not what it needs. The yellow could be due to a N-nitrogen defficiency, or it could be from not having enough p or k,( which are needed more in flowering, and less nitrogen is needed), what is the n-p-k ratio of your plant food?
Edit: I just looked at your second set of better pictures, and i would say it is mostly an N deficiency which you can tell by strictly yellowing, this will happen in the begining stages of flower and throughout, because they get less light and less nitrogen, you can keep them on by adding more nitrogen. and it may be missing some micronutrients and minerals that wouldnt be in the miracle grow nutes.