In order for Track Log to record automatically, make sure you have checked the following:

1.  Ensure that you have a GPS source connected.  If you have a WiFi only iPad, you will need an external GPS receiver.

2.  Open ForeFlight and go to MORE > SETTINGS > TRACK LOG and make sure the switch is ON next to ENABLE AUTO START/STOP.

3.  Make sure ForeFlight Mobile is open and running on your device and showing (in the foreground).

4.  Make sure the iPad is not asleep.  Of note, once a recording is started, the app can be backgrounded and/or the iPad can be allowed to sleep as long as you are using the internal GPS receiver or a Bluetooth external receiver.