False positive opk?

Has anyone experienced a false positive opk? Or know exactly what causes it. Im wondering if Im not actually releasing an egg. I get an lh surge every month and always have a dominant follicle. But its not looking classic on ultrasound for ovulation. So im confused why i would get an lh surge every month around the same time ( day 14/15) but not really be ovulating?? If that makes sense.