In your pictures, #3 & #5, show a rapid rooter plug in a Grodan 4" square delta block, sitting on some other media, probably coca.

Grodan makes rockwool, your form makes no mention of RW, where does that come into play? or do the pictures match the form?

IMHO your PH levels are too high. That alone could cause nutrient lock out as I mentioned above. Plus you probably burnt them first with the nutrients and additives. You should look into what Advance Nutrients reccomends as a ph level for coca coir/ rockwool or whatever you think you're growing in.

But why don't you go back to your guy at the shop and see what else he can sell you. I'm sure if you give him enough money, he'll solve your problem. I'm sure he sold you the Advance nutrients, Superthrive, Mother's Earth etc....