Looking to be a magnesium issue, dont be quick to assume that it is short on it if you have been adding it.
CalMag is notorious for causing a nutrient lockout so check the run off ph and ppm, if it's too high its a lockout and too low deficiency is the issue.
Coco and LED both burn through Calmag and if your feeding with tap water over time your root zone ph will rise as the chemicals react with co2 so for that reason it's good to deviate your ph watering.
Hope it helped