Yeah the more info you can share the better, but it looks like a possible nutrient/nitrogen burn, but are those autopots? I did some consulting for a grow running in autopots with coco, they had some somewhat similar issues with them- since its a bottom watering+feeding system that only brings water and nutrients to the plants and dosent allow for any runoff you need to be really carefull about your feed strength because you can get quite a lot of salt buildup in those bottom reserviors. I measured water in there with a 9+ EC on some of the plants, and ph was mostly in the 4's, suprisingly most seemed fairly healthy but others had various toxicity and lockout issues, similar to what your experiencing. What is your feed EC and PH in your main reservior? And can you take a sample of the nutrient solution thats in the bottom of the pots on the affected plants, and some healthier ones, and get ec and ph readings on those? If the readings you take indicate thats the issue I can tell you where to go from there.