I’m going to try swapping batteries and see if that makes a difference. I hope they offer to do something.
Mine is a pricey Campagnolo Stages. I’m a Campy guy and prefer an all campy bike but if I’m SOL with this I’m probably going to buy a Quarq or Power2Max.
Could also see if the firmware is up to date, in the stages app.
Conclusion - fixed!
I did a factory reset, installed a brand new Energizer battery, and ADC was 897.
It was weird that the old battery (also an Energizer) was being shown as having a full charge.
I guess when in doubt, install a fresh battery.