How long have they been in the same container? How large is the container? How old are the plants (including veg)? Have they ever been transplanted? Could be a rootbound issue where the plant isn't taking up any nutes. Yellowing from nitrogen def usually is just that, yellowing. The necrotic random splotches is what is suggesting to me that something is going on in your container, and if your PH is at 6.4, it may be rootbound. How long has it taken to progress to the level we see?

Just a thought for now, all the other specs you listed look good.