Occasionally this message is normal. The device assigns the positive or negative half wave to the channel and corrects that assignment when the current measurement calls it into question.

If the messages accumulate on one channel, noise in the current measurement may be simulating a current flow in half waves where none actually flows. First check whether any current flows through the channel at all – a heater that is not connected or is interrupted is the most common cause. If the messages persist, please contact customer service.