"Hi, I am having exactly the same issue. No matter what I do, I cannot get it to save the calibrated voltage. Do you have any idea what you did to fix it please?"
"I had the same issue. REsolved by connecting the Ground unit to laptop using FTDI. Then load settings in mission planner, as you would normally do with the air unit.Untick ECC & Op Resend. Save settings & try again."