Help with configuration

Hello,
I'm pretty new to Home assistant and Bermuda.
I'm trying to set up a simple presence system with bluetooth that tells me if my phone is home or not. I have an android with the Ha app installed and I have activated the BLE transmitter. At the moment I'm not interested in presence inside the single room. As a scanner I have set up a shelly and the bluetooth of the raspberry that are in the same room. The problem is that when I'm close to the scanner it continues to switch from unavailable to detected. If I move away even less than 10 meters the phone is not detected at all.
I don't know if I'm doing something wrong in the phone configurations or in Bermuda.