It looks like you have pre-trigger recording enabled, was it enabled prior to now? As in were you still experiencing this problem with it enabled?
If so, I would look at the actual motion detection windows and thresholds as the actual motion event may be recognized later than expected.
This thread goes over best practices on setting up VMD (video motion detection)
Make sure to follow the guidelines on the window shape especially. For outdoor cameras it is very important to limit potential false triggers as much as possible.
Do you have any clips occurring shortly before the motion events you are looking to capture actually happen?