2K video doorbell may not detect humans wearing hat

Just got this doorbell installed yesterday and had been working perfectly. I had it set to the lowest sensitivity to prevent nuance tripping. I only want to detect someone standing right in front of my door. My wife and I both tested it multiple times and it detected every time. Then the first time my mailman came right up to the door standing right in front of the camera - no detection. I thought what the heck. He always wears a hat. On a hunch I put on a hat and was able to walk right up to it w/o detection multiple times. After some experimenting I had to set the sensitivity back to the default setting (middle) in order to detect me wearing a hat. I have to admit I was not expecting that. Since most thieves wear hats it has to be able to detect someone wearing a hat. I hope I don’t start getting nuance tripping now.