Looks to be about 4 weeks into flower if it was a 10 week strain. So logic dictates something is slowing down development. I'm gonna rule out nutrients as the leave are healthy and in my experience nutrient deficiencys don't typically slow down flowering. There's many other things it could be but my guess is that light is the culprit, possibly not enough but more probably you have a level of light entering your grow room during your dark period. Frequent interruptions to your dark period will confuse your plant and can make your plant return to Vegetative growth either completely with your buds turning into brance sites and leaves slowly or partially which displays itself as an elongated and leafy harvest time, a constant leak of light into the room will have the same effect.
That's what I reckon about your 10 week grow could ne wrong though, what is the low down with your lights?