Fertile Period/Ovulation

Florence • Expecting baby #1 Dec 23!
I'm confused about the directives being generated by Glow. I rec'd a notification today that I should be ovulating and that the most important day for me to have sex is 3/31 in order to conceive, but according to the calendar function in Glow, my chance of conceiving is only 2% on 3/31. My highest chance of conceiving (around 23%) was on 3/25, per the Glow calendar. Does anyone know why my notification recommendation for when to have sex doesn't match my fertile day? Any advice would be welcome! Thanks so much!