I’ve not used the PI3 but I think there was a boot up option to disable the onboard bluetooth - can somebody else explain/help?
It seems the new version has move the Bluetooth - but it is still enabled.
sudo service bluetooth status:
Seems to work fine if I use a USB dongle in place of the build in BT. Strange though.
Have you got the newest version of the Python libraries installed?
This appears to have some info
The device name has changed for the internal BT chip /dev/ttyAMA0
although this used to clash with the emonhub chip/interface board.