If you flash, it will overwrite any changes you made to /etc/bluetooth/main.conf so you will need to redo that change. If you do OTA then it uses apt-get which will preserve those changes. olighak and Jan, can you try to redit /etc/bluetooth/main.conf and see whether that works. you will need to stop bluethood and start bluetoothd as root after you edit /etc/bluetooth/main.conf but you should not have to do that after reboots.