You're on a res, but in soilless. So automatic drip. What's your res like? Are you oxygenating it with something other than peroxide? Have you been checking the runoff pH out of the pots? I am guessing that if you did that, you would find it to be lower than desired. Something isn't right... obviously, lol. How long since the final re-pot do symptoms typically appear? My hunch is that your lime is used up and you are running low on calcium and the pH has dropped. Along with a stiff feeding schedule, those combine to give the symptoms you are seeing.
But check the runoff pH asap and let us know.