how reliable is glow for predicting ovulation?

Sixth cycle using glow and no baby yet . I had been on the pill for about 8 years as of September when I stopped taking it. Not sure if my body has gotten back into its normal  rhythm yet. I feel like glow has been wrong predicting ovulation as I have all of the physical symptoms of ovulation cm ect.... After the predicted days . ??? Anyone else have this issue?