That's alot of plants, but many of them seem to be showing or starting the same issue. I have never used the sensi line, so it's hard to comment on it, but i was thinking at first that the ph is too high and causing a lockout of heavier elements, namely iron, and/or, possible sulfur lacking. You have some purple veins on a few, which is usually not due to genetics, but either a lack of phosphorus, or magnesium to carry the phosphorus. I use pro mix as well...for me, i found 6.0-6.2 to be best..higher up, i had issues as well with tops.