If I may jump in.
I noticed you said these are in 2-gallon containers. They could have root rot depending on the size of your root system and what kind of drainage you have for any watering overage.
From your description, I also believe you could have an imbalance of nutrients due to not following recommended usage rates. It's ok to drop or raise the amount as you feel would help as long as it's done using the same proportions of all components. If you change the % amount for one nutrient, make sure amounts for all other nutrients coincide when it comes to ratios, otherwise, you can get lockout (which is what I believe to be the issue).
The nutrients have a very specific balance of primary NPK (Nitrogen, Phosphorus, and Potassium), secondary (Calcium, Magnesium, and Sulfur), along with micro-elements. This is why nutrients are created in A, B and sometimes 3 part. They only mix in specific proportions, otherwise, that dreaded lockout happens.
When you water, take notes as to what goes in regarding pH, ppm or ec (whatever method you use), and then check against runoff. If your runoff is much higher, I would flush a few times (until runoff matches the amount you originally used). If the amount is much higher, you know you have lockout.
I also recommend that you lower pH to 5.5.
I would definitely remove all yellow leaves (as long as completely yellow and dead).
Sorry that this was so long. Hope it helps.