2 diffeent ovulation apps

Jess • pround momvof two beautiful boys
So I have glow n a diffrent app . Glow said I'm ovulating 2morrow even tho my cm does not mimic that .. n the test says no.. but the other app says I'm ovulating the 15ths.. Both apps have my cycles for the past 8 months loaded .. A week diffrence is alot .. anyone else have this happen