Confused on ovulation date

I'm so confused GLOW tells me my ovulation date is 10/11 but I have 2 other apps that tell me I will ovulate on 10/12 . my cycle is a regular 28 day cycle so from my understanding I would ovulate on the 14th day which would be 10/12 (last period was 9/28)  is my math wrong or is GLOW wrong??!!  I'm so confused , I was told to have sex every OTHER day so I'm not sure if I should have sex on 10/11 or 10/12??!