I go along with the idea that the plant is not getting enough light.I'm thinking it should be showing sex by now period, auto or photo. I think the plant just isn't getting enough light to do anything meaningful.
A plant has to be sexually mature before it can start to show any pre-flowers or to start actively flowering. Also, there is the theory is that the plant has to start growing alternating nodes as a sign of sexual maturity.
This plant still has opposing nodes. No signs of pre-flowers and nothing else to indicate that it is mature enough to flower.
That too. Something else that came up earlier on page 1 and we seem to have left out of the discussion.I'm thinking you need to up-pot & fill it to the top this time also. The yellowing leaves are probably because it's rootbound in that 1/2 pot of soil.
Transplant to a larger pot. Prune some of the growth off to help get the plant into a more manageable size and shape. Put it under more light, either outside under the sun or add some more bulbs if keeping it inside. People have grown plants using just those curly-Q compact fluorescent bulbs.
If the group believes that it is actually a photo-period then doing this will not cause any problems and should actually help.