I agree with GrowngGrannie there is a lot of nitrogen going into this grow. the cal mg is also nitrogen leaning 2-0-0.
I think they are getting to much and their is a buildup in the medium, it needs a clean out. given that your in coir a flushing is on the table as a viable option.
If you are not watering till you get some runoff aorund 1/3, and if your allowing the plant to sit in its run off it might be to saturated with fertilizer. I would look into monitoring the EC of the runoff. Some users go up to 6.3 in flower on Hydro setups. But I feel you main issue is a buildup in the medium.
Best Of luck!
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