Once it's dark, all a camera can see is car headlights. While BI will trigger and save the alert, it then gets cancelled once past on to the AI.
Initially I just disabled AI for the camera concerned, however I now get the tens/hundreds of tree shadow alerts during the day which AI was able to cancel.
I can't figure out a simple way to not do the AI check after dark from within BI. An AI-check enable/disable feature based on time would be great, although this then brings up the problem of the constant change of sunset time.
I'm going to create a windows task to stop/start the AI service, but even if it works I don't think that's an very elegant solution and will certainly need constant changing as the months advance...