I had noticed my two batteries were drifting apart in terms of SOC over the past week or so, and that situation worsened considerably today, with BMS under AND over voltage notifications and general mayhem on SOC states.
On the off-chance that someone might be working at GE support on a Bank Holiday, I gave them a call this afternoon - and they were there, found an issue with a BMS register that had become "unticked" and so was not being read, sorted that and set a calibration run going.
Thanks Alessandro (sp?) - system looks fine now. I have to say that, whenever I have called support, (mainly to sort firmware update problems in the past tbh) they have done the job well for me - praise where it is due.