Sometimes.....you get a "auto" that is actually a photo. I had this in my Gelat.OG AUTO? diary. They were supposed to be auto seeds, but after 12 weeks they weren't flowering, as soon as I switched them to a 12/12 light cycle, they began flowering. It is either a mixup at the place where you got the seeds or not the most stable genetics.
I'd give it another week or 2, but if they haven't even sex'd yet, I'd put the one that isn't flowering into 12/12.