The relevant object category has not been selected during set up;

An Alert Zone has been set to exclude some areas;

The alerts have been turned off;

The Blindsight components have been installed inside metal housings that block wireless signals (a Faraday cage);

The sensors are not looking at the relevant area;

The sensors are covered or dirty;

Blindsight is not turned on or there is a power or connection issue;

There is a false negative.