No Rssi reported for BLE devices

I am trying to write an app which monitors distance to ble beacons using RSSI param. I faced an issue with RSSI reporting. When application first sees the device< all is OK. But any subsequent discoveries report rssi = 0 till the program restart.

I tried to recreate QBluetoothDeviceDiscoveryAgent for every rescan, but it didn't helped.

Also reproducing in 5.12.

See attachment for source code