BTW, I notice that you were using Ubuntu Linux as your host OS, and one common issue is that the usb udev rules might be not properly set up and thus the Arduino IDE may have no permission to access the debug interface over the USB port.
would you mind sharing your udev rules, usually from a file in:
/etc/udev/rules.d, and it may have some name like: /etc/udev/rules.d/10-arduino.rules or something else
