There is some really odd logic regarding the replay settings. It doesn't seem to correctly honour the number of files you set for specific event types. I never got to the bottom of it, but I also found that it would not save a race if you let the number of non-keep files reach their maximum on a different type (e.g. qualy). I now regularly keep and delete to ensure things are well under their max settings so replays don't go accidentally astray
I upped the max number of the event types in CM so hopefully that sorts it. I've had it chop the start off races before but never not record anything. All i changed was the quality. I had finally started to get full races on the minimum quality setting - 8Hz but wanted to see what difference the quality made. I am running vr in low settings so I'm not sure it's possible to get replays in high settings