There may be the following reasons：
1. The device has no power at that time;
2. No SD card / SD card failure at that time;
3. The SD card has limited capacity and the video was overwritten. After micro SD card is full, the latest video will overwrite the earliest video;
4. Failed to load, you can refresh (select time again) and retry.
Solution: please change a high-quality card or choose our cloud service which is more stable.