That’s interesting. The feature works great for me. I block out a section, then I can walk and jump in that area and it never triggers. I have some busy areas blocked out and it never triggers on those areas as far as I can tell.
Suggestion: This is just a guess, but try resetting the camera to default settings, block out the area, then see if it doesn’t trigger using the default settings.
One other thing I did notice. If a vehicle, like a UPS truck, casts a shadow into an area that is not blocked out - the shadow can trigger the camera.
Note: Checking my cameras, they are running FW ver 2.151