Glow wrongly moved AF up. Why?

Kelly • writer . wife . new mama
Midway thru my Aug cycle, Glow moved my AF start date from 9/3 to 9/1. When 9/1 came and went with no sign of AF I was excited for a possible BFP. So I was totally bummed when my AF showed up on my original start date, today, 9/3. 
​Any idea why Glow would do this? My fertility window didn't change so I don't get why they would move my AF start date -- and unnecessarily get my hopes up. Really don't want to go thru that again next month.