I had some solicitors come to my driveway and my camera missed it. It picked them up pulling in at 4:15. I talked to them for around 5 min and it wasn’t recorded. Another camera has me walking back at 4;21. 6 minutes complete missed.
Do you have a paid subscription like Cam Plus or Cam unlimited. ? If not there is usually a 5 min. period the camera will not record after the first short event. No pay, no play. 
Worth noting if you have an SD card and no subscription, it will still record every motion event even during the 5 minutes. It just won’t “tag” it as an event and you have to go to the sd card and look for the green spots to view the video.
I have cam unlimited and a sd card. Not sure why this happens
Does that particular cam successfully record to the cloud? It may be that it isn’t associated with the subscription, though I believe I’ve seen people say that with unlimited, you can’t actually remove cams from the subscription, so if that’s true it shouldn’t be the problem.
If the motion never stopped it would have just considered it all one event and it should all be on the card (and in the cloud). If you go to the SD card screen and navigate the timeline, is it solid green (or maybe multiple sections of green with small breaks)?