I would suspect that maybe youre experiencing ph lockout. If theres not enough calcium/ lime then the acidity of the peat moss can cause the ph to drop below acceptable levels for mj to thrive. Couple that with poor ph'ed water and or over watering and it really gets bad.
When I build the soil from scratch I'm adding a mix of Lime/Gypsum/Oyster shell flour.
But, these were grown in a fresh batch.
I'm going to do a slurry test and see just where its at because I think you may be right. The liming agents may not be fully available yet and/or I need to up the ratios.
To me, it seems as though the cations are off and the plant is struggling with uptake...especially K.
I hope I get to that "supercharged" soil with more runs...or at least before my frustration takes over and drives me back to the bottles.
Oh and honestly, I don't think the Down to Earth dry amendments are the best quality I could be using. Seems as though my other sources last quite a bit longer.