We know LEDs exacerbate our plant's tendency for magnesium deficency. Perhaps an overabundance of a particular spectrum could lead to a K deficiency, or cause an imbalance in the ratio of Mg and Ca (leading to an abundance of Ca causing a K deficiency). Too much N can cause a K deficiency too (I've read).
I would hit it with more K, reduce any calmag you're using (since you don't seem to have a ca/mg deficiency).
If you want to explore how one LED light could trigger a deficiency while another doesn't, start a thread in the Indoor->LED forum. If you could get StarDustSailor's attention, he'd probably blow your mind with details about what's happening.