Nutrient lock out?

by going back in diary, i'd say it is related to watering habits. when you water, it is important to ensure entirity of pot gets wet. some runoff is needed. when fertilizing full strength, ~20% runoff is a good goal. As you ramp up to that point, you don't want to leech the soil of its nutrients, but some runoff is inevitable. Dry pockets and such, even when slightly underfed, can cause all sorts of problems with pH and concentration of nutes. pH of 6.8.. slightly acidic is goal - with or without nutrients mixed. In this case if the next irrigation was just water, i'd get some runoff and continue normal cycle of fertilization as recommended above. Don't have to do anything crazy, but i wouldn't start with fertilization on first cycle. Wait for top 1" to dry. Feel weight of pot. Get familiar with it. That's your signal to irrigate again... with or without fertlizer.. you plants looked fine. possible tip burn prior. You could lighten up 5-10% on dose and stick to your pattern before.. but with these new behaviours.