
by no means put the good ones under 12/12, that will badly compromise yield and quality! The stubborn one is likely showing some "incomplete" auto expression, it's absolutely not a black and white thing, no off/on switch there,... We see many examples of this here all the time... sometimes it's just plain bad luck, or poor breeding,... you say this is Growers Choice?

Figures! I'm seeing several misfires from their shaggy-ass genetics recently, no exaggeration.... I don't like to bag on breeders, UNLESS there's real empirical evidence of consistent problems, and IMO, now there is,.... you must be the 3rd or 4th person with this problem of lagging, slow blooming auto's of theirs that I alone have had to help with....
So, you can let her be for say, another week and see if the crowns start forming, or gut out a 12/12 cycle however you can.... or just junk her however disappointing that is,... Sometimes the cheaper seeds are no damn bargain at all,.... Stay with known quality genetics from here out, we have all the proof and research right here!