I don't know of anyone else using AHP equipment near me. The closest is 3 floors away and about 50 feet down the hall of that floor. The setup I have at home works fine.
This indicates to me this setup is in an apt or office building which would mean metal studwork, door frames and more .
Lots of metal is a known RF signal blocker a large metal object like a fridge between the two will stop the signal from reaching the CM15.
Have you tested the sensor beside the Cm15 with a clear line of sight between the two?
If it fails to work next to the Cm15 the issue is the sensor.
If it works slowly move farther away keeping the line of sight between the two clear.
The SR751 RF repeater may solve your issue if the sensor is working and it looks like something is blocking the signal.
You would need to keep the line of sight clear between the repeater and the motion sensor as well a clear line of sight from the repeater to the Cm15