I have similar issues from the beggining and initial firmwares.
For example 2-4 meters from camera I draw region area for Motion and on exact same area I draw Intrusion Detection.
Motion detection on 20 or 40 detects every kind and every size of target inside this area Human or not.
In same area Intrusion Detection some times does not detect target at minimum and max size(not set), at lowest validity, at max 100 "sensitivity"(percentage of target size), at lowest validity(basic). And I am not talking about insects but for Humans.
Detection for Smart events should always exist and this is not a matter of Sensitivity or target size or validity. The target must always be Detected(its the D on DORI), processed(Observed, Recognized or Identified) and give Alarm according to our Settings and what we want to give an Alarm.
For example the target will give an alarm after loittering for 5 secongs inside the area but the Detection and Rectangle surrounding the target should exist 5 seconds before Alarm.
Possibly this issue has to do with the way of movement. Straight line ahead, sideways, diagonal, making rounds. An insect for example flying around is Detected. A Human quickly(not running) passing by this area is not detected. Possibly the reason is the position of the camera or the light, sun or other, in the area. But this cannot be an excuse because the Motion(Basic events) Detects. So this is definitely the firmware. The very strange thing is that the far targets at 10 meters distance are always detected. Nothing is missed.
And yes. Cats and sparrows many many times are detected as Humans.