Paling inside-out and top down indicates an issue with low sulfur. Symptoms are not discrete. So, could be lockout, pH related,or lacking around the roots. Usually lockout is messy and impacts other molecules before sulfur, so i'd wager it's simply low sulfur.
It's hydo, so if you are familiar with your PPMS, not just overall concentration, should be easy to pick out. I've never played around with S levels, but i never have issues around ~100ppm. This depends slightly on the ratio and concentration of other nutritional elements, but if anywhere near a healthy formula, should be in the same ballpark.
The ratios and concentration of nutritional elements around the roots is about being available, not necessarily the ratio in which they are used inside the plant. It's an important concept to understand and can help make better decisions and avoid mythological madness.