Had a negative opk before and during my ovulation last month. Has this happened to anyone else and why?!

Eva_f 🌿 • 🤰🏻bb#1 • Endometriosis warrior🎗

Using clear blue digital got a peak CD13 then lows CD16,17,18 but BBT shows I definitely didn't ovulate until cd18/19. Got same peak day cycle before too but wasn't tracking BBT so don't know when I ov'd. Anyone have any insights please!