I don't know how else to explain it but corrupt, but for the first time in the 16 months or so we've been using this camera, we got back to the office and found a bad clip. In most programs, it would open up as black video, no audio. Some programs (media encoder, for instance) would see a single frame.
We put the card back in the camera to see if it could play it back and it showed a ? as the thumbnail.
The good news is that when you selected the clip in camera, the two options you are given are to delete it or recover it. I chose recover and after a few minutes, the clip was totally fine. Transferred it to the computer and all is well.
So my question is: what happened? Has anyone else ever run into this? Any best practices to avoid it?
No. It was really weird. I was nearing the end of the card and we were shooting an interview, so I notified the director before he asked the next question, cut, switched cards, and rolled again. At the end of the last couple of questions, I cut and found out it hadn't recorded anything on the new card. It wasn't actually rolling. So we did another take of the last few questions and everything worked fine that time.
So at the end of one card, that clip was corrupt, and at the beginning of the next card the first clip didn't record at all.