Runoff ph is the only ph that matters in terms of diagnosing a plant in my opinion. I'm no expert either, but at 5.6 that plant can't take in anything.
I also have a feeling that there is a reason OP didn't post pics. It's not a "new" thing. He's ph'ing the water and then adding those particular nutes (which happen to lower ph even more). If he's been watering at a 6.8 ph like he suggests, there is no way the runoff could be that low with that blend.
Fox farms ocean buffers between 6.3-6.5. If he was adding the correct ph from the beginning, it would be physically impossible to have that low of a ph.
I think there is a lot more OP isn't saying, especially with no pics. However, I could be wrong I guess.