Could just be a seed mix up. I assumed that's what happened with my Feminised RQS Bubble Kush Auto from Herbie's.
You can pull the non flowering one out each day and lock her in a closet for 12 hours. See if she triggers flowering. Then figure out if you wanna keep her and drop the lights to 14/10 or something.
Or if she's a photo you could let her keep vegging, flip to flower when the autos finish and you should have a pretty hefty photo period to flower by then.
Some morning Bush.
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