I would like to read the tx power level of BLE beacons with my M5Stack ESP32.
I get the rssi value but I would like to know the transmission power. I do not mean the 1Byte "transmitted/measured power" that you should receive on 1m range. I mean the power level that determines how strongly the beacon sends its broadcast (what the max. range should be).

I would like to read whether the beacon is configurated to send only at e.g. max. range of 2m or maybe 15m.

I use Arduino and PlatformIO with int8_t BLEAdvertisedDevice::getTXPower ()
http://www.neilkolban.com/esp32/docs/cpp_utils/html/class_b_l_e_advertised_device.html#a8c62ba653ba4f6fb904b6bc195620511

And I always get txPower: 0. using haveTXPower() returns false. But my smartphone with the usuals apps displays without and problems the txPower value (e.g. -20dBm that would indicate the ble beacon has only few meters max. range)

Did anyone had success with a M5Stack to read those txPower values?
Is there any code snippet that REALLY WORKS? There are planty online but they show 0 txPower and false on haveTxPower.

greetings

edit: further infos from platformIO
PLATFORM: Espressif 32 > M5Stack Core ESP32
HARDWARE: ESP32 240MHz 320KB RAM (4MB Flash)
Libs: M5Stack 0.2.5