Seems like theres plenty of nitrogen in your formula especially for a bloom booster. Do you know the ph of your runoff? I don’t grow in coco, never have but i know ph’ing your solution to 6.3 is too high for it. Treat it the same as hydro and ph your solution to 5.8 as its a completely soilless medium and should be treated as one, ph wise.
A high root zone ph could be causing nutrient lockouts/excess of other nutrients