Black Kow is a thermophilic compost, PH shouldn't be a problem. If it was unfinished manure I could see it might be a PH problem or turn into an anaerobic smelly mess.
What I was thinking is whether 40% of the stuff was causing too much water retention without adding additional perlite or whatever. If the roots are too wet, the same symptoms of nutrient deficiencies can occur when there are no actual nutrient deficiencies in the soil.
I wouldn't think that would happen in Smart Pots since they drain and dry out faster than plastic containers. Actually the same symptoms can occur if the roots are too dry too.
Bruce, we are all speculating as to what the cause is based on your description.
I just don't see that actual nutrients could be the problem as long as you are fertilizing with TTF as directed.