So why bother adding any coco at all?
Personally, I'd never use fux farms, but if I did I doubt I'd mix it with anything other than a peat based soiless mix like sunshine #4 or promix hp to 'cool it down' some.
It's really hard to say what your issue is. It's clearly a nutrient deficiency, but what is the underlying issue. Fux farm has nutrient in it so she should be getting food, but she's not. Ph plays a big role in nutrient absorption, so if your medium ph is out of whack then you can add all the nutrients you want the plant ain't getting them and all you're doing is compiling nutrients making a more toxic environment (super high ec) in the medium.
Coco should be treated like hydroponics. Soil is opposite. So you're combining two opposite styles into one pot. Imo, your issue lies in your medium choice. GL