I use Happy Frog. My best suggestion is to lift the pot when it's dry, and feel the weight of it dry so you'll know when to water. In a few of your photos the plants look parched, and are weeping. At this stage in the grow it would be wise to fully water the plants. I do this with Happy Frog myself personally, and at this stage of growth they should be starting to need water every other day. Let those roots expand, the fabric pots will air prune the roots. In my experience, Happy Frog needs amended around day 21-25, and every 10-14 thereafter. Some plants may need it weekly though, especially late in flower.I'm trying Real hard to be positive and supportive here !
Chances are it isn't the mix but your watering that is the issue. Wet/dry is hard to judge in a final pot without some experience.
The only issue I have with Happy Frog is determining when and how much additional food to give.
Hope this helps!