Okay. Before the latest app update my cycle length was 28 days (even though my avg is 30 days) and my fertile window was Oct 1-7. After the update my cycle length switched to 31 days (still not my average) but it's also shifted my fertile window. It's telling me my ovulation date was the  9th of October when it was previously the 4th.  Now my bbt would suggest the ovulation happened on the 5th? Lowest bbt before a steady climb.