I read about Lightmix on the BioBizz website and a few other blurbs. It says you can control the growth of your plants with nutes by cutting back or giving larger quantities to. Something about the ingredients breaking down salts in a productive way? Sounds like a no brainer except that 'larger quantities' bit. Overdosing, if you will.
I am shooting at the moon, if you will, again when I say this: Maybe give a good dose of veg nutes to get N back in? Maybe yours is a strain that needs more N during flowering? Always go with what the majority say. I look too deep into things.