I reformat the sd card after I download each session. I have never had a corrupted file. Might be why. Since you have to erase the files anyways, it seems like a good idea to reformat each time.
After a few weeks of great videos we had this issue again this week. I formatted 2 cards to have a backup. When the first one stopped working, I went to the backup. It recorded a few races, and on the final race it not only didn’t record, but it deleted all of the files again. So we we lost all of the heat races.
I guess I need to download the videos off the camera after each race from now on.