Recordings detect object but object disappears even though recording continues

I decided to look at some recordings that are basically vehicles drving down my street. On several recordings, I see the initial vehicle but it disappears even though NCS keeps recording for the interval. It shows say an 18 second video but all I see is the detected vehicle then it freezes and disppears. What could be the problem? The CPU is always very low and I only have the one camera.

Most likely the encoder need more cpu power. In Settings and tab Encoding change the number of threads between Auto and 8 and see what works best.
Since it’s traffic you might need to increase FPS.