Some possible reasons resulting in low RF signals and shorten the distance of transmission leading to the invisibility of Helium Hotspots include:

Obstacles, including buildings, mountains, and forestry in a comparatively dense environment;

Possible Electromagnetic Interference, Line of Sight Interference, Fresnel Zone Interference, or RF Interference existing around cities;

Weather Conditions;

System Operating Margin, Shadowing, and or Link Badger.

Please refer to where should COTX X3 be installed?