Please keep us updated. I’ve had 12V issues similar to you but the underlying cause was said to be missing CAN messages which caused the DC converter to disconnect and kill the 12V. I asked if it could be software related and they seemed to think no.
Thankfully I know CAN! But to me that doesn't sound good....
Missing CAN messages, meaning, like the DC/DC converter stopped receiving messages from MCU/(whatever system communicates with it, assuming is it MCU though), or the MCU isn't actually sending the message? Which end was the issue, if you know? - Hopefully it is software, I am very eager to get my 3 back.
Have you had any issues after the initial one? I really hope this is not an on going thing....
Did they update you to a different software afterwards?