how far away are you with the light from the plant?
It could be a light burn issue. This usually results in lighter colored tips, while when it comes to nutrient burns, the tips are usually dark and die off.
Also nutrient burn can normally be seen on multiple areas of the plant, while light-burn is normally just on the buds closest to the light (unless your light is much too bright, so the PPFD even at the lower branches is too high).