Did you buy non brick coco, meaning they flushed it and de-bricked it for ya? ( bagged version) cause your issue looks like salt poisoning and wrong ph related/overwater since salt is probably halting everything
(bagged coco)Issue with that is some of the companies don't flush that well or buy overly salty coco. Plus a huge negative factor is contaminants since they are mixing it ( only takes one bad brick) .. So my tip is buy proper branded brick if that's the issue obviosuly and wash the coco ( theres tons of FAQ/TUT) for purging your coco before use!
anyways good luck