Major stress from growing for weeks at 24/0 is the problem!
All plants, autoflowering cannabis included, NEED sleep to finish its photosynthesis cycle and have a correctly functioning metabolism.
A plant with an incorrectly functioning metabolism will NEVER grow to its best potential.
Without sleep, some plants will just grow and grow and grow without flowering because they can't tell what is going on, just one endless day.
Topping and recovery have nothing to do with this issue, your plant is not sulking!
The issue is a messed up metabolism and not having ever had the chance to complete her daily photosynthesis cycle.
A great deal of things occur during the dark period that is vital to a plants well being, without sleep, these things can not happen.
Go to the optimum lighting schedule of 18/6 and if she didn't start flowering within a couple of weeks, I would be very surprised.
This will not affect your other plant negatively either.
Next time, if growing autos, go with 18/6 from day one to harvest day, this is the optimum light/dark schedule.
Your plants will be MUCH healthier, grow more and the buds more potent.......all because sleep is vital for plant health.
Also, go easy on the defoliation (more leaves = more growth) and I would also advise against topping autos in the future too.
The MYTH that it is ok to grow for weeks/months without sleep NEEDS to be removed from the growing world ASAP!
Hope this helps, Organoman.