I've had some problems with 2 sessions on my S3.
1st session wouldn't connect to GPS but a restart fixed this.
2nd session worked fine until I went to review the data afterwards and it wiped all the session data. All files in the session folder are 0kb in size. One slightly odd thing I did was end the session and immediately switch the phone off as the battery was low.
Tim
Comments
2) Sounds like some of the write buffers in the operating system were not flushed before the phone powered off. How long was the session you lost?
PS. RaceChrono writes 1000 plots at a time, so you can lose up to 17 minutes on 1 Hz GPS and 2 minutes on 10 Hz GPS, if the phone powers off while recording. But it does flush the buffers immediately when you end the session...