pH flux? Nute deficiency?

Slight burnt tips in flower is relatively normal. When the hormones switch over they dont need as much nutrients going into flower and they dont need as much nitrogen so what's left in the medium becomes enough to burn the tips of your leaves. It's not a bad thing as long as you start out real easy on your flower nutes and increase as neccessary. When your on a proper watering regiment and you know how much you have fed (starting low and increasing) and when watered having 20% runoff to keep salts from building, and you see something funky going on, you now know that it's from the plants wanting more food. Only you know how much food you have given her and how much plain water, so only you would know if there is a deficiency or it is lockout. If your following the feeding directions on the label of your nutes, it is probably lockout. Hope this was informative for ya. Cheers