Beyond the technical and tangible aspects of gardening are the emotional and intangible components.
That plant is not happy. Perhaps it was vegged too long for its productive lifespan. Or perhaps the em field from drawing 20K watts vs. 1k watts is having an adverse impact. Was it always the plant on the end? Maybe it was the location within the room. What is on the other side of the wall? I cannot make an accurate judgement of your space using only my eyes and therfor cannot diagnose any problem.
If you think any of those Ideas are too far out there, just stop reading.
Is it because the light produced by led is more particle than wave? What about your energy and attitude? Arey you still running hps/hid elesewhere? Are the balasts or drivers creating radiation fields we have not properly evaluated? Cheap noisy electronics in soundsystems annoy the fuck out of me but go unnoticed by others, is the same thing happening to that plant? Is the room or tray oriented so that plants not getting the same hydraulic action as the others? Ok, so that last one is technical and tangible, but its not something that can be seen in pics.
@hybridway2 has there been any change in the rate at wich you cull plants under led? Curious if you may have been unintentionally filtering the plants exhibiting undesireable traits?