Did you just name ALL the base nutrients as a probable cause? You can't answer a multiple choice question with "Well, it's either A B or C... and maybe D too"
[OP]
(Your cal-mag isn't that organic nonsense is it?) Checking Ph regularly, not just at fill? Ph'ing for...... dirt? (try bumping just a touch higher?) All else fails, mix up a massive batch of nutes, and fully flush the pots to reset their Ph and nutreint levels to what you need... (This is why I stopped growing in bug cities..... er, dirt)
Well Cal/Mag helps uptake NPK too so sometimes feeding extra cal/mag can help with any npk deff
but no the plants clearly are not burnt from over feeding so personally I would feed them more Potassium and some more cal/mag
I don`t really care personally about losing some lower fan leaves so feeding extra N would not be an issue and I worry about calcium phosphate build up in my root zone personally so I like to use bacteria that brakes that down and try not to over do it with the phosphorus personally...... you know as handy and cheap as monopotassium phosphate is I normally just add some potassium sulphate to a good flowering mix I`ve already concocted
Obviously looking at the plants the loss of colour is caused by a lack of N or K, cal/mag can help with that
Did I start saying borbon, copper ? zinc ? maganses ? silicone ? nope ok the plant probably would not cry if it got a bit more of them too
but mostly cal/mag and extra K would probably do it
but looking like some extra veg feed is needed for the 1st 2 weeks or so of flower and the OP should try a little cal/mag and potassium sulphate
but you know what ??? He grew it he knows what he fed it
I can cut it down to 3 to 6 things he could feed more of next time that`s gotta be loads of help
Multiple choice ? really ? what if the plant needs all fucking 3 ? hell if I was there I could probably find 100`s of things to do to make it "better next time"
likely going to have to take them early since they are basically fuct. 
