The old witches broom!
Did you ever try cutting your light on hours down to see if it would help it bloom? From all I have read about the long winded sativas it seems they sometimes need either a 11/13 or 10/14 light schedule to properly bloom and finish. If you do decide to run it again maybe give it a go and see if it helps.
The longest running strains i have run went 16 weeks after flip and both did awful. I should have tried lowering my light on time to see if it helped. Funny enough both plants were supposed to have a 9 week finish time. 16 weeks after flip and nothing but garbage from both. One was cannalope haze and the other was violetta.
My Shackzilla was a 15 week strain but she at least put out.